Actual source code: sfcuda.cu

      1: #include <../src/vec/is/sf/impls/basic/sfpack.h>

      3: /* Map a thread id to an index in root/leaf space through a series of 3D subdomains. See PetscSFPackOpt. */
      4: __device__ static inline PetscInt MapTidToIndex(const PetscInt *opt,PetscInt tid)
      5: {
      6:   PetscInt        i,j,k,m,n,r;
      7:   const PetscInt  *offset,*start,*dx,*dy,*X,*Y;

      9:   n      = opt[0];
     10:   offset = opt + 1;
     11:   start  = opt + n + 2;
     12:   dx     = opt + 2*n + 2;
     13:   dy     = opt + 3*n + 2;
     14:   X      = opt + 5*n + 2;
     15:   Y      = opt + 6*n + 2;
     16:   for (r=0; r<n; r++) {if (tid < offset[r+1]) break;}
     17:   m = (tid - offset[r]);
     18:   k = m/(dx[r]*dy[r]);
     19:   j = (m - k*dx[r]*dy[r])/dx[r];
     20:   i = m - k*dx[r]*dy[r] - j*dx[r];

     22:   return (start[r] + k*X[r]*Y[r] + j*X[r] + i);
     23: }

     25: /*====================================================================================*/
     26: /*  Templated CUDA kernels for pack/unpack. The Op can be regular or atomic           */
     27: /*====================================================================================*/

     29: /* Suppose user calls PetscSFReduce(sf,unit,...) and <unit> is an MPI data type made of 16 PetscReals, then
     30:    <Type> is PetscReal, which is the primitive type we operate on.
     31:    <bs>   is 16, which says <unit> contains 16 primitive types.
     32:    <BS>   is 8, which is the maximal SIMD width we will try to vectorize operations on <unit>.
     33:    <EQ>   is 0, which is (bs == BS ? 1 : 0)

     35:   If instead, <unit> has 8 PetscReals, then bs=8, BS=8, EQ=1, rendering MBS below to a compile time constant.
     36:   For the common case in VecScatter, bs=1, BS=1, EQ=1, MBS=1, the inner for-loops below will be totally unrolled.
     37: */
     38: template<class Type,PetscInt BS,PetscInt EQ>
     39: __global__ static void d_Pack(PetscInt bs,PetscInt count,PetscInt start,const PetscInt *opt,const PetscInt *idx,const Type *data,Type *buf)
     40: {
     41:   PetscInt        i,s,t,tid = blockIdx.x*blockDim.x + threadIdx.x;
     42:   const PetscInt  grid_size = gridDim.x * blockDim.x;
     43:   const PetscInt  M = (EQ) ? 1 : bs/BS; /* If EQ, then M=1 enables compiler's const-propagation */
     44:   const PetscInt  MBS = M*BS;  /* MBS=bs. We turn MBS into a compile-time const when EQ=1. */

     46:   for (; tid<count; tid += grid_size) {
     47:     /* opt != NULL ==> idx == NULL, i.e., the indices have patterns but not contiguous;
     48:        opt == NULL && idx == NULL ==> the indices are contiguous;
     49:      */
     50:     t = (opt? MapTidToIndex(opt,tid) : (idx? idx[tid] : start+tid))*MBS;
     51:     s = tid*MBS;
     52:     for (i=0; i<MBS; i++) buf[s+i] = data[t+i];
     53:   }
     54: }

     56: template<class Type,class Op,PetscInt BS,PetscInt EQ>
     57: __global__ static void d_UnpackAndOp(PetscInt bs,PetscInt count,PetscInt start,const PetscInt *opt,const PetscInt *idx,Type *data,const Type *buf)
     58: {
     59:   PetscInt        i,s,t,tid = blockIdx.x*blockDim.x + threadIdx.x;
     60:   const PetscInt  grid_size = gridDim.x * blockDim.x;
     61:   const PetscInt  M = (EQ) ? 1 : bs/BS, MBS = M*BS;
     62:   Op              op;

     64:   for (; tid<count; tid += grid_size) {
     65:     t = (opt? MapTidToIndex(opt,tid) : (idx? idx[tid] : start+tid))*MBS;
     66:     s = tid*MBS;
     67:     for (i=0; i<MBS; i++) op(data[t+i],buf[s+i]);
     68:   }
     69: }

     71: template<class Type,class Op,PetscInt BS,PetscInt EQ>
     72: __global__ static void d_FetchAndOp(PetscInt bs,PetscInt count,PetscInt rootstart,const PetscInt *rootopt,const PetscInt *rootidx,Type *rootdata,Type *leafbuf)
     73: {
     74:   PetscInt        i,l,r,tid = blockIdx.x*blockDim.x + threadIdx.x;
     75:   const PetscInt  grid_size = gridDim.x * blockDim.x;
     76:   const PetscInt  M = (EQ) ? 1 : bs/BS, MBS = M*BS;
     77:   Op              op;

     79:   for (; tid<count; tid += grid_size) {
     80:     r = (rootopt? MapTidToIndex(rootopt,tid) : (rootidx? rootidx[tid] : rootstart+tid))*MBS;
     81:     l = tid*MBS;
     82:     for (i=0; i<MBS; i++) leafbuf[l+i] = op(rootdata[r+i],leafbuf[l+i]);
     83:   }
     84: }

     86: template<class Type,class Op,PetscInt BS,PetscInt EQ>
     87: __global__ static void d_ScatterAndOp(PetscInt bs,PetscInt count,PetscInt srcx,PetscInt srcy,PetscInt srcX,PetscInt srcY,PetscInt srcStart,const PetscInt* srcIdx,const Type *src,PetscInt dstx,PetscInt dsty,PetscInt dstX,PetscInt dstY,PetscInt dstStart,const PetscInt *dstIdx,Type *dst)
     88: {
     89:   PetscInt        i,j,k,s,t,tid = blockIdx.x*blockDim.x + threadIdx.x;
     90:   const PetscInt  grid_size = gridDim.x * blockDim.x;
     91:   const PetscInt  M = (EQ) ? 1 : bs/BS, MBS = M*BS;
     92:   Op              op;

     94:   for (; tid<count; tid += grid_size) {
     95:     if (!srcIdx) { /* src is either contiguous or 3D */
     96:       k = tid/(srcx*srcy);
     97:       j = (tid - k*srcx*srcy)/srcx;
     98:       i = tid - k*srcx*srcy - j*srcx;
     99:       s = srcStart + k*srcX*srcY + j*srcX + i;
    100:     } else {
    101:       s = srcIdx[tid];
    102:     }

    104:     if (!dstIdx) { /* dst is either contiguous or 3D */
    105:       k = tid/(dstx*dsty);
    106:       j = (tid - k*dstx*dsty)/dstx;
    107:       i = tid - k*dstx*dsty - j*dstx;
    108:       t = dstStart + k*dstX*dstY + j*dstX + i;
    109:     } else {
    110:       t = dstIdx[tid];
    111:     }

    113:     s *= MBS;
    114:     t *= MBS;
    115:     for (i=0; i<MBS; i++) op(dst[t+i],src[s+i]);
    116:   }
    117: }

    119: template<class Type,class Op,PetscInt BS,PetscInt EQ>
    120: __global__ static void d_FetchAndOpLocal(PetscInt bs,PetscInt count,PetscInt rootstart,const PetscInt *rootopt,const PetscInt *rootidx,Type *rootdata,PetscInt leafstart,const PetscInt *leafopt,const PetscInt *leafidx,const Type *leafdata,Type *leafupdate)
    121: {
    122:   PetscInt        i,l,r,tid = blockIdx.x*blockDim.x + threadIdx.x;
    123:   const PetscInt  grid_size = gridDim.x * blockDim.x;
    124:   const PetscInt  M = (EQ) ? 1 : bs/BS, MBS = M*BS;
    125:   Op              op;

    127:   for (; tid<count; tid += grid_size) {
    128:     r = (rootopt? MapTidToIndex(rootopt,tid) : (rootidx? rootidx[tid] : rootstart+tid))*MBS;
    129:     l = (leafopt? MapTidToIndex(leafopt,tid) : (leafidx? leafidx[tid] : leafstart+tid))*MBS;
    130:     for (i=0; i<MBS; i++) leafupdate[l+i] = op(rootdata[r+i],leafdata[l+i]);
    131:   }
    132: }

    134: /*====================================================================================*/
    135: /*                             Regular operations on device                           */
    136: /*====================================================================================*/
    137: template<typename Type> struct Insert {__device__ Type operator() (Type& x,Type y) const {Type old = x; x  = y;             return old;}};
    138: template<typename Type> struct Add    {__device__ Type operator() (Type& x,Type y) const {Type old = x; x += y;             return old;}};
    139: template<typename Type> struct Mult   {__device__ Type operator() (Type& x,Type y) const {Type old = x; x *= y;             return old;}};
    140: template<typename Type> struct Min    {__device__ Type operator() (Type& x,Type y) const {Type old = x; x  = PetscMin(x,y); return old;}};
    141: template<typename Type> struct Max    {__device__ Type operator() (Type& x,Type y) const {Type old = x; x  = PetscMax(x,y); return old;}};
    142: template<typename Type> struct LAND   {__device__ Type operator() (Type& x,Type y) const {Type old = x; x  = x && y;        return old;}};
    143: template<typename Type> struct LOR    {__device__ Type operator() (Type& x,Type y) const {Type old = x; x  = x || y;        return old;}};
    144: template<typename Type> struct LXOR   {__device__ Type operator() (Type& x,Type y) const {Type old = x; x  = !x != !y;      return old;}};
    145: template<typename Type> struct BAND   {__device__ Type operator() (Type& x,Type y) const {Type old = x; x  = x & y;         return old;}};
    146: template<typename Type> struct BOR    {__device__ Type operator() (Type& x,Type y) const {Type old = x; x  = x | y;         return old;}};
    147: template<typename Type> struct BXOR   {__device__ Type operator() (Type& x,Type y) const {Type old = x; x  = x ^ y;         return old;}};
    148: template<typename Type> struct Minloc {
    149:   __device__ Type operator() (Type& x,Type y) const {
    150:     Type old = x;
    151:     if (y.a < x.a) x = y;
    152:     else if (y.a == x.a) x.b = min(x.b,y.b);
    153:     return old;
    154:   }
    155: };
    156: template<typename Type> struct Maxloc {
    157:   __device__ Type operator() (Type& x,Type y) const {
    158:     Type old = x;
    159:     if (y.a > x.a) x = y;
    160:     else if (y.a == x.a) x.b = min(x.b,y.b); /* See MPI MAXLOC */
    161:     return old;
    162:   }
    163: };

    165: /*====================================================================================*/
    166: /*                             Atomic operations on device                            */
    167: /*====================================================================================*/

    169: /*
    170:   Atomic Insert (exchange) operations

    172:   CUDA C Programming Guide V10.1 Chapter B.12.1.3:

    174:   int atomicExch(int* address, int val);
    175:   unsigned int atomicExch(unsigned int* address, unsigned int val);
    176:   unsigned long long int atomicExch(unsigned long long int* address, unsigned long long int val);
    177:   float atomicExch(float* address, float val);

    179:   reads the 32-bit or 64-bit word old located at the address address in global or shared
    180:   memory and stores val back to memory at the same address. These two operations are
    181:   performed in one atomic transaction. The function returns old.

    183:   PETSc notes:

    185:   It may be useful in PetscSFFetchAndOp with op = MPI_REPLACE.

    187:   VecScatter with multiple entries scattered to the same location using INSERT_VALUES does not need
    188:   atomic insertion, since it does not need the old value. A 32-bit or 64-bit store instruction should
    189:   be atomic itself.

    191:   With bs>1 and a unit > 64 bits, the current element-wise atomic approach can not guarantee the whole
    192:   insertion is atomic. Hope no user codes rely on that.
    193: */
    194: __device__ static double atomicExch(double* address,double val) {return __longlong_as_double(atomicExch((ullint*)address,__double_as_longlong(val)));}

    196: __device__ static llint atomicExch(llint* address,llint val) {return (llint)(atomicExch((ullint*)address,(ullint)val));}

    198: template<typename Type> struct AtomicInsert {__device__ Type operator() (Type& x,Type y) const {return atomicExch(&x,y);}};

    200: #if defined(PETSC_HAVE_COMPLEX)
    201: #if defined(PETSC_USE_REAL_DOUBLE)
    202: /* CUDA does not support 128-bit atomics. Users should not insert different 128-bit PetscComplex values to the same location */
    203: template<> struct AtomicInsert<PetscComplex> {
    204:   __device__ PetscComplex operator() (PetscComplex& x,PetscComplex y) const {
    205:     PetscComplex         old, *z = &old;
    206:     double               *xp = (double*)&x,*yp = (double*)&y;
    207:     AtomicInsert<double> op;
    208:     z[0] = op(xp[0],yp[0]);
    209:     z[1] = op(xp[1],yp[1]);
    210:     return old; /* The returned value may not be atomic. It can be mix of two ops. Caller should discard it. */
    211:   }
    212: };
    213: #elif defined(PETSC_USE_REAL_SINGLE)
    214: template<> struct AtomicInsert<PetscComplex> {
    215:   __device__ PetscComplex operator() (PetscComplex& x,PetscComplex y) const {
    216:     double               *xp = (double*)&x,*yp = (double*)&y;
    217:     AtomicInsert<double> op;
    218:     return op(xp[0],yp[0]);
    219:   }
    220: };
    221: #endif
    222: #endif

    224: /*
    225:   Atomic add operations

    227:   CUDA C Programming Guide V10.1 Chapter B.12.1.1:

    229:   int atomicAdd(int* address, int val);
    230:   unsigned int atomicAdd(unsigned int* address,unsigned int val);
    231:   unsigned long long int atomicAdd(unsigned long long int* address,unsigned long long int val);
    232:   float atomicAdd(float* address, float val);
    233:   double atomicAdd(double* address, double val);
    234:   __half2 atomicAdd(__half2 *address, __half2 val);
    235:   __half atomicAdd(__half *address, __half val);

    237:   reads the 16-bit, 32-bit or 64-bit word old located at the address address in global or shared memory, computes (old + val),
    238:   and stores the result back to memory at the same address. These three operations are performed in one atomic transaction. The
    239:   function returns old.

    241:   The 32-bit floating-point version of atomicAdd() is only supported by devices of compute capability 2.x and higher.
    242:   The 64-bit floating-point version of atomicAdd() is only supported by devices of compute capability 6.x and higher.
    243:   The 32-bit __half2 floating-point version of atomicAdd() is only supported by devices of compute capability 6.x and
    244:   higher. The atomicity of the __half2 add operation is guaranteed separately for each of the two __half elements;
    245:   the entire __half2 is not guaranteed to be atomic as a single 32-bit access.
    246:   The 16-bit __half floating-point version of atomicAdd() is only supported by devices of compute capability 7.x and higher.
    247: */
    248: __device__ static llint atomicAdd(llint* address,llint val) {return (llint)atomicAdd((ullint*)address,(ullint)val);}

    250: template<typename Type> struct AtomicAdd {__device__ Type operator() (Type& x,Type y) const {return atomicAdd(&x,y);}};

    252: template<> struct AtomicAdd<double> {
    253:   __device__ double operator() (double& x,double y) const {
    254: #if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 600)
    255:     return atomicAdd(&x,y);
    256: #else
    257:     double *address = &x, val = y;
    258:     ullint *address_as_ull = (ullint*)address;
    259:     ullint old = *address_as_ull, assumed;
    260:     do {
    261:       assumed = old;
    262:       old     = atomicCAS(address_as_ull, assumed, __double_as_longlong(val + __longlong_as_double(assumed)));
    263:       /* Note: uses integer comparison to avoid hang in case of NaN (since NaN !=NaN) */
    264:     } while (assumed != old);
    265:     return __longlong_as_double(old);
    266: #endif
    267:   }
    268: };

    270: template<> struct AtomicAdd<float> {
    271:   __device__ float operator() (float& x,float y) const {
    272: #if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 200)
    273:     return atomicAdd(&x,y);
    274: #else
    275:     float *address = &x, val = y;
    276:     int   *address_as_int = (int*)address;
    277:     int   old = *address_as_int, assumed;
    278:     do {
    279:       assumed = old;
    280:       old     = atomicCAS(address_as_int, assumed, __float_as_int(val + __int_as_float(assumed)));
    281:       /* Note: uses integer comparison to avoid hang in case of NaN (since NaN !=NaN) */
    282:     } while (assumed != old);
    283:     return __int_as_float(old);
    284: #endif
    285:   }
    286: };

    288: #if defined(PETSC_HAVE_COMPLEX)
    289: template<> struct AtomicAdd<PetscComplex> {
    290:  __device__ PetscComplex operator() (PetscComplex& x,PetscComplex y) const {
    291:   PetscComplex         old, *z = &old;
    292:   PetscReal            *xp = (PetscReal*)&x,*yp = (PetscReal*)&y;
    293:   AtomicAdd<PetscReal> op;
    294:   z[0] = op(xp[0],yp[0]);
    295:   z[1] = op(xp[1],yp[1]);
    296:   return old; /* The returned value may not be atomic. It can be mix of two ops. Caller should discard it. */
    297:  }
    298: };
    299: #endif

    301: /*
    302:   Atomic Mult operations:

    304:   CUDA has no atomicMult at all, so we build our own with atomicCAS
    305:  */
    306: #if defined(PETSC_USE_REAL_DOUBLE)
    307: __device__ static double atomicMult(double* address, double val)
    308: {
    309:   ullint *address_as_ull = (ullint*)(address);
    310:   ullint old = *address_as_ull, assumed;
    311:   do {
    312:     assumed = old;
    313:     /* Other threads can access and modify value of *address_as_ull after the read above and before the write below */
    314:     old     = atomicCAS(address_as_ull, assumed, __double_as_longlong(val*__longlong_as_double(assumed)));
    315:   } while (assumed != old);
    316:   return __longlong_as_double(old);
    317: }
    318: #elif defined(PETSC_USE_REAL_SINGLE)
    319: __device__ static float atomicMult(float* address,float val)
    320: {
    321:   int *address_as_int = (int*)(address);
    322:   int old = *address_as_int, assumed;
    323:   do {
    324:     assumed  = old;
    325:     old      = atomicCAS(address_as_int, assumed, __float_as_int(val*__int_as_float(assumed)));
    326:   } while (assumed != old);
    327:   return __int_as_float(old);
    328: }
    329: #endif

    331: __device__ static int atomicMult(int* address,int val)
    332: {
    333:   int *address_as_int = (int*)(address);
    334:   int old = *address_as_int, assumed;
    335:   do {
    336:     assumed = old;
    337:     old     = atomicCAS(address_as_int, assumed, val*assumed);
    338:   } while (assumed != old);
    339:   return (int)old;
    340: }

    342: __device__ static llint atomicMult(llint* address,llint val)
    343: {
    344:   ullint *address_as_ull = (ullint*)(address);
    345:   ullint old = *address_as_ull, assumed;
    346:   do {
    347:     assumed = old;
    348:     old     = atomicCAS(address_as_ull, assumed, (ullint)(val*(llint)assumed));
    349:   } while (assumed != old);
    350:   return (llint)old;
    351: }

    353: template<typename Type> struct AtomicMult {__device__ Type operator() (Type& x,Type y) const {return atomicMult(&x,y);}};

    355: /*
    356:   Atomic Min/Max operations

    358:   CUDA C Programming Guide V10.1 Chapter B.12.1.4~5:

    360:   int atomicMin(int* address, int val);
    361:   unsigned int atomicMin(unsigned int* address,unsigned int val);
    362:   unsigned long long int atomicMin(unsigned long long int* address,unsigned long long int val);

    364:   reads the 32-bit or 64-bit word old located at the address address in global or shared
    365:   memory, computes the minimum of old and val, and stores the result back to memory
    366:   at the same address. These three operations are performed in one atomic transaction.
    367:   The function returns old.
    368:   The 64-bit version of atomicMin() is only supported by devices of compute capability 3.5 and higher.

    370:   atomicMax() is similar.
    371:  */

    373: #if defined(PETSC_USE_REAL_DOUBLE)
    374: __device__ static double atomicMin(double* address, double val)
    375: {
    376:   ullint *address_as_ull = (ullint*)(address);
    377:   ullint old = *address_as_ull, assumed;
    378:   do {
    379:     assumed = old;
    380:     old     = atomicCAS(address_as_ull, assumed, __double_as_longlong(PetscMin(val,__longlong_as_double(assumed))));
    381:   } while (assumed != old);
    382:   return __longlong_as_double(old);
    383: }

    385: __device__ static double atomicMax(double* address, double val)
    386: {
    387:   ullint *address_as_ull = (ullint*)(address);
    388:   ullint old = *address_as_ull, assumed;
    389:   do {
    390:     assumed  = old;
    391:     old = atomicCAS(address_as_ull, assumed, __double_as_longlong(PetscMax(val,__longlong_as_double(assumed))));
    392:   } while (assumed != old);
    393:   return __longlong_as_double(old);
    394: }
    395: #elif defined(PETSC_USE_REAL_SINGLE)
    396: __device__ static float atomicMin(float* address,float val)
    397: {
    398:   int *address_as_int = (int*)(address);
    399:   int old = *address_as_int, assumed;
    400:   do {
    401:     assumed = old;
    402:     old     = atomicCAS(address_as_int, assumed, __float_as_int(PetscMin(val,__int_as_float(assumed))));
    403:   } while (assumed != old);
    404:   return __int_as_float(old);
    405: }

    407: __device__ static float atomicMax(float* address,float val)
    408: {
    409:   int *address_as_int = (int*)(address);
    410:   int old = *address_as_int, assumed;
    411:   do {
    412:     assumed = old;
    413:     old     = atomicCAS(address_as_int, assumed, __float_as_int(PetscMax(val,__int_as_float(assumed))));
    414:   } while (assumed != old);
    415:   return __int_as_float(old);
    416: }
    417: #endif

    419: /*
    420:   atomicMin/Max(long long *, long long) are not in Nvidia's documentation. But on OLCF Summit we found
    421:   atomicMin/Max/And/Or/Xor(long long *, long long) in /sw/summit/cuda/10.1.243/include/sm_32_atomic_functions.h.
    422:   This causes compilation errors with pgi compilers and 64-bit indices:
    423:       error: function "atomicMin(long long *, long long)" has already been defined

    425:   So we add extra conditions defined(__CUDA_ARCH__) && (__CUDA_ARCH__ < 320)
    426: */
    427: #if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ < 320)
    428: __device__ static llint atomicMin(llint* address,llint val)
    429: {
    430:   ullint *address_as_ull = (ullint*)(address);
    431:   ullint old = *address_as_ull, assumed;
    432:   do {
    433:     assumed = old;
    434:     old     = atomicCAS(address_as_ull, assumed, (ullint)(PetscMin(val,(llint)assumed)));
    435:   } while (assumed != old);
    436:   return (llint)old;
    437: }

    439: __device__ static llint atomicMax(llint* address,llint val)
    440: {
    441:   ullint *address_as_ull = (ullint*)(address);
    442:   ullint old = *address_as_ull, assumed;
    443:   do {
    444:     assumed = old;
    445:     old     = atomicCAS(address_as_ull, assumed, (ullint)(PetscMax(val,(llint)assumed)));
    446:   } while (assumed != old);
    447:   return (llint)old;
    448: }
    449: #endif

    451: template<typename Type> struct AtomicMin {__device__ Type operator() (Type& x,Type y) const {return atomicMin(&x,y);}};
    452: template<typename Type> struct AtomicMax {__device__ Type operator() (Type& x,Type y) const {return atomicMax(&x,y);}};

    454: /*
    455:   Atomic bitwise operations

    457:   CUDA C Programming Guide V10.1 Chapter B.12.2.1 ~ B.12.2.3:

    459:   int atomicAnd(int* address, int val);
    460:   unsigned int atomicAnd(unsigned int* address,unsigned int val);
    461:   unsigned long long int atomicAnd(unsigned long long int* address,unsigned long long int val);

    463:   reads the 32-bit or 64-bit word old located at the address address in global or shared
    464:   memory, computes (old & val), and stores the result back to memory at the same
    465:   address. These three operations are performed in one atomic transaction.
    466:   The function returns old.

    468:   The 64-bit version of atomicAnd() is only supported by devices of compute capability 3.5 and higher.

    470:   atomicOr() and atomicXor are similar.
    471: */

    473: #if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ < 320) /* Why 320? see comments at atomicMin() above */
    474: __device__ static llint atomicAnd(llint* address,llint val)
    475: {
    476:   ullint *address_as_ull = (ullint*)(address);
    477:   ullint old = *address_as_ull, assumed;
    478:   do {
    479:     assumed = old;
    480:     old     = atomicCAS(address_as_ull, assumed, (ullint)(val & (llint)assumed));
    481:   } while (assumed != old);
    482:   return (llint)old;
    483: }
    484: __device__ static llint atomicOr(llint* address,llint val)
    485: {
    486:   ullint *address_as_ull = (ullint*)(address);
    487:   ullint old = *address_as_ull, assumed;
    488:   do {
    489:     assumed = old;
    490:     old     = atomicCAS(address_as_ull, assumed, (ullint)(val | (llint)assumed));
    491:   } while (assumed != old);
    492:   return (llint)old;
    493: }

    495: __device__ static llint atomicXor(llint* address,llint val)
    496: {
    497:   ullint *address_as_ull = (ullint*)(address);
    498:   ullint old = *address_as_ull, assumed;
    499:   do {
    500:     assumed = old;
    501:     old     = atomicCAS(address_as_ull, assumed, (ullint)(val ^ (llint)assumed));
    502:   } while (assumed != old);
    503:   return (llint)old;
    504: }
    505: #endif

    507: template<typename Type> struct AtomicBAND {__device__ Type operator() (Type& x,Type y) const {return atomicAnd(&x,y);}};
    508: template<typename Type> struct AtomicBOR  {__device__ Type operator() (Type& x,Type y) const {return atomicOr (&x,y);}};
    509: template<typename Type> struct AtomicBXOR {__device__ Type operator() (Type& x,Type y) const {return atomicXor(&x,y);}};

    511: /*
    512:   Atomic logical operations:

    514:   CUDA has no atomic logical operations at all. We support them on integer types.
    515: */

    517: /* A template without definition makes any instantiation not using given specializations erroneous at compile time,
    518:    which is what we want since we only support 32-bit and 64-bit integers.
    519:  */
    520: template<typename Type,class Op,int size/* sizeof(Type) */> struct AtomicLogical;

    522: template<typename Type,class Op>
    523: struct AtomicLogical<Type,Op,4> {
    524:   __device__ Type operator()(Type& x,Type y) const {
    525:     int *address_as_int = (int*)(&x);
    526:     int old = *address_as_int, assumed;
    527:     Op op;
    528:     do {
    529:       assumed = old;
    530:       old     = atomicCAS(address_as_int, assumed, (int)(op((Type)assumed,y)));
    531:     } while (assumed != old);
    532:     return (Type)old;
    533:   }
    534: };

    536: template<typename Type,class Op>
    537: struct AtomicLogical<Type,Op,8> {
    538:   __device__ Type operator()(Type& x,Type y) const {
    539:     ullint *address_as_ull = (ullint*)(&x);
    540:     ullint old = *address_as_ull, assumed;
    541:     Op op;
    542:     do {
    543:       assumed = old;
    544:       old     = atomicCAS(address_as_ull, assumed, (ullint)(op((Type)assumed,y)));
    545:     } while (assumed != old);
    546:     return (Type)old;
    547:   }
    548: };

    550: /* Note land/lor/lxor below are different from LAND etc above. Here we pass arguments by value and return result of ops (not old value) */
    551: template<typename Type> struct land {__device__ Type operator()(Type x, Type y) {return x && y;}};
    552: template<typename Type> struct lor  {__device__ Type operator()(Type x, Type y) {return x || y;}};
    553: template<typename Type> struct lxor {__device__ Type operator()(Type x, Type y) {return (!x != !y);}};

    555: template<typename Type> struct AtomicLAND {__device__ Type operator()(Type& x,Type y) const {AtomicLogical<Type,land<Type>,sizeof(Type)> op; return op(x,y);}};
    556: template<typename Type> struct AtomicLOR  {__device__ Type operator()(Type& x,Type y) const {AtomicLogical<Type,lor<Type> ,sizeof(Type)> op; return op(x,y);}};
    557: template<typename Type> struct AtomicLXOR {__device__ Type operator()(Type& x,Type y) const {AtomicLogical<Type,lxor<Type>,sizeof(Type)> op; return op(x,y);}};

    559: /*====================================================================================*/
    560: /*  Wrapper functions of cuda kernels. Function pointers are stored in 'link'         */
    561: /*====================================================================================*/
    562: template<typename Type,PetscInt BS,PetscInt EQ>
    563: static PetscErrorCode Pack(PetscSFLink link,PetscInt count,PetscInt start,PetscSFPackOpt opt,const PetscInt *idx,const void *data,void *buf)
    564: {
    565:   PetscInt           nthreads=256;
    566:   PetscInt           nblocks=(count+nthreads-1)/nthreads;
    567:   const PetscInt     *iarray=opt ? opt->array : NULL;

    569:   if (!count) return 0;
    570:   if (!opt && !idx) { /* It is a 'CUDA data to nvshmem buf' memory copy */
    571:     cudaMemcpyAsync(buf,(char*)data+start*link->unitbytes,count*link->unitbytes,cudaMemcpyDeviceToDevice,link->stream);
    572:   } else {
    573:     nblocks = PetscMin(nblocks,link->maxResidentThreadsPerGPU/nthreads);
    574:     d_Pack<Type,BS,EQ><<<nblocks,nthreads,0,link->stream>>>(link->bs,count,start,iarray,idx,(const Type*)data,(Type*)buf);
    575:     cudaGetLastError();
    576:   }
    577:   return 0;
    578: }

    580: /* To specialize UnpackAndOp for the cudaMemcpyAsync() below. Usually if this is a contiguous memcpy, we use root/leafdirect and do
    581:    not need UnpackAndOp. Only with nvshmem, we need this 'nvshmem buf to CUDA data' memory copy
    582: */
    583: template<typename Type,PetscInt BS,PetscInt EQ>
    584: static PetscErrorCode Unpack(PetscSFLink link,PetscInt count,PetscInt start,PetscSFPackOpt opt,const PetscInt *idx,void *data,const void *buf)
    585: {
    586:   PetscInt           nthreads=256;
    587:   PetscInt           nblocks=(count+nthreads-1)/nthreads;
    588:   const PetscInt     *iarray=opt ? opt->array : NULL;

    590:   if (!count) return 0;
    591:   if (!opt && !idx) { /* It is a 'nvshmem buf to CUDA data' memory copy */
    592:     cudaMemcpyAsync((char*)data+start*link->unitbytes,buf,count*link->unitbytes,cudaMemcpyDeviceToDevice,link->stream);
    593:   } else {
    594:     nblocks = PetscMin(nblocks,link->maxResidentThreadsPerGPU/nthreads);
    595:     d_UnpackAndOp<Type,Insert<Type>,BS,EQ><<<nblocks,nthreads,0,link->stream>>>(link->bs,count,start,iarray,idx,(Type*)data,(const Type*)buf);
    596:     cudaGetLastError();
    597:   }
    598:   return 0;
    599: }

    601: template<typename Type,class Op,PetscInt BS,PetscInt EQ>
    602: static PetscErrorCode UnpackAndOp(PetscSFLink link,PetscInt count,PetscInt start,PetscSFPackOpt opt,const PetscInt *idx,void *data,const void *buf)
    603: {
    604:   PetscInt           nthreads=256;
    605:   PetscInt           nblocks=(count+nthreads-1)/nthreads;
    606:   const PetscInt     *iarray=opt ? opt->array : NULL;

    608:   if (!count) return 0;
    609:   nblocks = PetscMin(nblocks,link->maxResidentThreadsPerGPU/nthreads);
    610:   d_UnpackAndOp<Type,Op,BS,EQ><<<nblocks,nthreads,0,link->stream>>>(link->bs,count,start,iarray,idx,(Type*)data,(const Type*)buf);
    611:   cudaGetLastError();
    612:   return 0;
    613: }

    615: template<typename Type,class Op,PetscInt BS,PetscInt EQ>
    616: static PetscErrorCode FetchAndOp(PetscSFLink link,PetscInt count,PetscInt start,PetscSFPackOpt opt,const PetscInt *idx,void *data,void *buf)
    617: {
    618:   PetscInt           nthreads=256;
    619:   PetscInt           nblocks=(count+nthreads-1)/nthreads;
    620:   const PetscInt     *iarray=opt ? opt->array : NULL;

    622:   if (!count) return 0;
    623:   nblocks = PetscMin(nblocks,link->maxResidentThreadsPerGPU/nthreads);
    624:   d_FetchAndOp<Type,Op,BS,EQ><<<nblocks,nthreads,0,link->stream>>>(link->bs,count,start,iarray,idx,(Type*)data,(Type*)buf);
    625:   cudaGetLastError();
    626:   return 0;
    627: }

    629: template<typename Type,class Op,PetscInt BS,PetscInt EQ>
    630: static PetscErrorCode ScatterAndOp(PetscSFLink link,PetscInt count,PetscInt srcStart,PetscSFPackOpt srcOpt,const PetscInt *srcIdx,const void *src,PetscInt dstStart,PetscSFPackOpt dstOpt,const PetscInt *dstIdx,void *dst)
    631: {
    632:   PetscInt           nthreads=256;
    633:   PetscInt           nblocks=(count+nthreads-1)/nthreads;
    634:   PetscInt           srcx=0,srcy=0,srcX=0,srcY=0,dstx=0,dsty=0,dstX=0,dstY=0;

    636:   if (!count) return 0;
    637:   nblocks = PetscMin(nblocks,link->maxResidentThreadsPerGPU/nthreads);

    639:   /* The 3D shape of source subdomain may be different than that of the destination, which makes it difficult to use CUDA 3D grid and block */
    640:   if (srcOpt)       {srcx = srcOpt->dx[0]; srcy = srcOpt->dy[0]; srcX = srcOpt->X[0]; srcY = srcOpt->Y[0]; srcStart = srcOpt->start[0]; srcIdx = NULL;}
    641:   else if (!srcIdx) {srcx = srcX = count; srcy = srcY = 1;}

    643:   if (dstOpt)       {dstx = dstOpt->dx[0]; dsty = dstOpt->dy[0]; dstX = dstOpt->X[0]; dstY = dstOpt->Y[0]; dstStart = dstOpt->start[0]; dstIdx = NULL;}
    644:   else if (!dstIdx) {dstx = dstX = count; dsty = dstY = 1;}

    646:   d_ScatterAndOp<Type,Op,BS,EQ><<<nblocks,nthreads,0,link->stream>>>(link->bs,count,srcx,srcy,srcX,srcY,srcStart,srcIdx,(const Type*)src,dstx,dsty,dstX,dstY,dstStart,dstIdx,(Type*)dst);
    647:   cudaGetLastError();
    648:   return 0;
    649: }

    651: /* Specialization for Insert since we may use cudaMemcpyAsync */
    652: template<typename Type,PetscInt BS,PetscInt EQ>
    653: static PetscErrorCode ScatterAndInsert(PetscSFLink link,PetscInt count,PetscInt srcStart,PetscSFPackOpt srcOpt,const PetscInt *srcIdx,const void *src,PetscInt dstStart,PetscSFPackOpt dstOpt,const PetscInt *dstIdx,void *dst)
    654: {
    655:   if (!count) return 0;
    656:   /*src and dst are contiguous */
    657:   if ((!srcOpt && !srcIdx) && (!dstOpt && !dstIdx) && src != dst) {
    658:     cudaMemcpyAsync((Type*)dst+dstStart*link->bs,(const Type*)src+srcStart*link->bs,count*link->unitbytes,cudaMemcpyDeviceToDevice,link->stream);
    659:   } else {
    660:     ScatterAndOp<Type,Insert<Type>,BS,EQ>(link,count,srcStart,srcOpt,srcIdx,src,dstStart,dstOpt,dstIdx,dst);
    661:   }
    662:   return 0;
    663: }

    665: template<typename Type,class Op,PetscInt BS,PetscInt EQ>
    666: static PetscErrorCode FetchAndOpLocal(PetscSFLink link,PetscInt count,PetscInt rootstart,PetscSFPackOpt rootopt,const PetscInt *rootidx,void *rootdata,PetscInt leafstart,PetscSFPackOpt leafopt,const PetscInt *leafidx,const void *leafdata,void *leafupdate)
    667: {
    668:   PetscInt          nthreads=256;
    669:   PetscInt          nblocks=(count+nthreads-1)/nthreads;
    670:   const PetscInt    *rarray = rootopt ? rootopt->array : NULL;
    671:   const PetscInt    *larray = leafopt ? leafopt->array : NULL;

    673:   if (!count) return 0;
    674:   nblocks = PetscMin(nblocks,link->maxResidentThreadsPerGPU/nthreads);
    675:   d_FetchAndOpLocal<Type,Op,BS,EQ><<<nblocks,nthreads,0,link->stream>>>(link->bs,count,rootstart,rarray,rootidx,(Type*)rootdata,leafstart,larray,leafidx,(const Type*)leafdata,(Type*)leafupdate);
    676:   cudaGetLastError();
    677:   return 0;
    678: }

    680: /*====================================================================================*/
    681: /*  Init various types and instantiate pack/unpack function pointers                  */
    682: /*====================================================================================*/
    683: template<typename Type,PetscInt BS,PetscInt EQ>
    684: static void PackInit_RealType(PetscSFLink link)
    685: {
    686:   /* Pack/unpack for remote communication */
    687:   link->d_Pack              = Pack<Type,BS,EQ>;
    688:   link->d_UnpackAndInsert   = Unpack<Type,BS,EQ>;
    689:   link->d_UnpackAndAdd      = UnpackAndOp     <Type,Add<Type>         ,BS,EQ>;
    690:   link->d_UnpackAndMult     = UnpackAndOp     <Type,Mult<Type>        ,BS,EQ>;
    691:   link->d_UnpackAndMin      = UnpackAndOp     <Type,Min<Type>         ,BS,EQ>;
    692:   link->d_UnpackAndMax      = UnpackAndOp     <Type,Max<Type>         ,BS,EQ>;
    693:   link->d_FetchAndAdd       = FetchAndOp      <Type,Add<Type>         ,BS,EQ>;

    695:   /* Scatter for local communication */
    696:   link->d_ScatterAndInsert  = ScatterAndInsert<Type                   ,BS,EQ>; /* Has special optimizations */
    697:   link->d_ScatterAndAdd     = ScatterAndOp    <Type,Add<Type>         ,BS,EQ>;
    698:   link->d_ScatterAndMult    = ScatterAndOp    <Type,Mult<Type>        ,BS,EQ>;
    699:   link->d_ScatterAndMin     = ScatterAndOp    <Type,Min<Type>         ,BS,EQ>;
    700:   link->d_ScatterAndMax     = ScatterAndOp    <Type,Max<Type>         ,BS,EQ>;
    701:   link->d_FetchAndAddLocal  = FetchAndOpLocal <Type,Add <Type>        ,BS,EQ>;

    703:   /* Atomic versions when there are data-race possibilities */
    704:   link->da_UnpackAndInsert  = UnpackAndOp     <Type,AtomicInsert<Type>,BS,EQ>;
    705:   link->da_UnpackAndAdd     = UnpackAndOp     <Type,AtomicAdd<Type>   ,BS,EQ>;
    706:   link->da_UnpackAndMult    = UnpackAndOp     <Type,AtomicMult<Type>  ,BS,EQ>;
    707:   link->da_UnpackAndMin     = UnpackAndOp     <Type,AtomicMin<Type>   ,BS,EQ>;
    708:   link->da_UnpackAndMax     = UnpackAndOp     <Type,AtomicMax<Type>   ,BS,EQ>;
    709:   link->da_FetchAndAdd      = FetchAndOp      <Type,AtomicAdd<Type>   ,BS,EQ>;

    711:   link->da_ScatterAndInsert = ScatterAndOp    <Type,AtomicInsert<Type>,BS,EQ>;
    712:   link->da_ScatterAndAdd    = ScatterAndOp    <Type,AtomicAdd<Type>   ,BS,EQ>;
    713:   link->da_ScatterAndMult   = ScatterAndOp    <Type,AtomicMult<Type>  ,BS,EQ>;
    714:   link->da_ScatterAndMin    = ScatterAndOp    <Type,AtomicMin<Type>   ,BS,EQ>;
    715:   link->da_ScatterAndMax    = ScatterAndOp    <Type,AtomicMax<Type>   ,BS,EQ>;
    716:   link->da_FetchAndAddLocal = FetchAndOpLocal <Type,AtomicAdd<Type>   ,BS,EQ>;
    717: }

    719: /* Have this templated class to specialize for char integers */
    720: template<typename Type,PetscInt BS,PetscInt EQ,PetscInt size/*sizeof(Type)*/>
    721: struct PackInit_IntegerType_Atomic {
    722:   static void Init(PetscSFLink link)
    723:   {
    724:     link->da_UnpackAndInsert  = UnpackAndOp<Type,AtomicInsert<Type>,BS,EQ>;
    725:     link->da_UnpackAndAdd     = UnpackAndOp<Type,AtomicAdd<Type>   ,BS,EQ>;
    726:     link->da_UnpackAndMult    = UnpackAndOp<Type,AtomicMult<Type>  ,BS,EQ>;
    727:     link->da_UnpackAndMin     = UnpackAndOp<Type,AtomicMin<Type>   ,BS,EQ>;
    728:     link->da_UnpackAndMax     = UnpackAndOp<Type,AtomicMax<Type>   ,BS,EQ>;
    729:     link->da_UnpackAndLAND    = UnpackAndOp<Type,AtomicLAND<Type>  ,BS,EQ>;
    730:     link->da_UnpackAndLOR     = UnpackAndOp<Type,AtomicLOR<Type>   ,BS,EQ>;
    731:     link->da_UnpackAndLXOR    = UnpackAndOp<Type,AtomicLXOR<Type>  ,BS,EQ>;
    732:     link->da_UnpackAndBAND    = UnpackAndOp<Type,AtomicBAND<Type>  ,BS,EQ>;
    733:     link->da_UnpackAndBOR     = UnpackAndOp<Type,AtomicBOR<Type>   ,BS,EQ>;
    734:     link->da_UnpackAndBXOR    = UnpackAndOp<Type,AtomicBXOR<Type>  ,BS,EQ>;
    735:     link->da_FetchAndAdd      = FetchAndOp <Type,AtomicAdd<Type>   ,BS,EQ>;

    737:     link->da_ScatterAndInsert = ScatterAndOp<Type,AtomicInsert<Type>,BS,EQ>;
    738:     link->da_ScatterAndAdd    = ScatterAndOp<Type,AtomicAdd<Type>   ,BS,EQ>;
    739:     link->da_ScatterAndMult   = ScatterAndOp<Type,AtomicMult<Type>  ,BS,EQ>;
    740:     link->da_ScatterAndMin    = ScatterAndOp<Type,AtomicMin<Type>   ,BS,EQ>;
    741:     link->da_ScatterAndMax    = ScatterAndOp<Type,AtomicMax<Type>   ,BS,EQ>;
    742:     link->da_ScatterAndLAND   = ScatterAndOp<Type,AtomicLAND<Type>  ,BS,EQ>;
    743:     link->da_ScatterAndLOR    = ScatterAndOp<Type,AtomicLOR<Type>   ,BS,EQ>;
    744:     link->da_ScatterAndLXOR   = ScatterAndOp<Type,AtomicLXOR<Type>  ,BS,EQ>;
    745:     link->da_ScatterAndBAND   = ScatterAndOp<Type,AtomicBAND<Type>  ,BS,EQ>;
    746:     link->da_ScatterAndBOR    = ScatterAndOp<Type,AtomicBOR<Type>   ,BS,EQ>;
    747:     link->da_ScatterAndBXOR   = ScatterAndOp<Type,AtomicBXOR<Type>  ,BS,EQ>;
    748:     link->da_FetchAndAddLocal = FetchAndOpLocal<Type,AtomicAdd<Type>,BS,EQ>;
    749:   }
    750: };

    752: /* CUDA does not support atomics on chars. It is TBD in PETSc. */
    753: template<typename Type,PetscInt BS,PetscInt EQ>
    754: struct PackInit_IntegerType_Atomic<Type,BS,EQ,1> {
    755:   static void Init(PetscSFLink link) {/* Nothing to leave function pointers NULL */}
    756: };

    758: template<typename Type,PetscInt BS,PetscInt EQ>
    759: static void PackInit_IntegerType(PetscSFLink link)
    760: {
    761:   link->d_Pack            = Pack<Type,BS,EQ>;
    762:   link->d_UnpackAndInsert = Unpack<Type,BS,EQ>;
    763:   link->d_UnpackAndAdd    = UnpackAndOp<Type,Add<Type>   ,BS,EQ>;
    764:   link->d_UnpackAndMult   = UnpackAndOp<Type,Mult<Type>  ,BS,EQ>;
    765:   link->d_UnpackAndMin    = UnpackAndOp<Type,Min<Type>   ,BS,EQ>;
    766:   link->d_UnpackAndMax    = UnpackAndOp<Type,Max<Type>   ,BS,EQ>;
    767:   link->d_UnpackAndLAND   = UnpackAndOp<Type,LAND<Type>  ,BS,EQ>;
    768:   link->d_UnpackAndLOR    = UnpackAndOp<Type,LOR<Type>   ,BS,EQ>;
    769:   link->d_UnpackAndLXOR   = UnpackAndOp<Type,LXOR<Type>  ,BS,EQ>;
    770:   link->d_UnpackAndBAND   = UnpackAndOp<Type,BAND<Type>  ,BS,EQ>;
    771:   link->d_UnpackAndBOR    = UnpackAndOp<Type,BOR<Type>   ,BS,EQ>;
    772:   link->d_UnpackAndBXOR   = UnpackAndOp<Type,BXOR<Type>  ,BS,EQ>;
    773:   link->d_FetchAndAdd     = FetchAndOp <Type,Add<Type>   ,BS,EQ>;

    775:   link->d_ScatterAndInsert = ScatterAndInsert<Type,BS,EQ>;
    776:   link->d_ScatterAndAdd    = ScatterAndOp<Type,Add<Type>   ,BS,EQ>;
    777:   link->d_ScatterAndMult   = ScatterAndOp<Type,Mult<Type>  ,BS,EQ>;
    778:   link->d_ScatterAndMin    = ScatterAndOp<Type,Min<Type>   ,BS,EQ>;
    779:   link->d_ScatterAndMax    = ScatterAndOp<Type,Max<Type>   ,BS,EQ>;
    780:   link->d_ScatterAndLAND   = ScatterAndOp<Type,LAND<Type>  ,BS,EQ>;
    781:   link->d_ScatterAndLOR    = ScatterAndOp<Type,LOR<Type>   ,BS,EQ>;
    782:   link->d_ScatterAndLXOR   = ScatterAndOp<Type,LXOR<Type>  ,BS,EQ>;
    783:   link->d_ScatterAndBAND   = ScatterAndOp<Type,BAND<Type>  ,BS,EQ>;
    784:   link->d_ScatterAndBOR    = ScatterAndOp<Type,BOR<Type>   ,BS,EQ>;
    785:   link->d_ScatterAndBXOR   = ScatterAndOp<Type,BXOR<Type>  ,BS,EQ>;
    786:   link->d_FetchAndAddLocal = FetchAndOpLocal<Type,Add<Type>,BS,EQ>;
    787:   PackInit_IntegerType_Atomic<Type,BS,EQ,sizeof(Type)>::Init(link);
    788: }

    790: #if defined(PETSC_HAVE_COMPLEX)
    791: template<typename Type,PetscInt BS,PetscInt EQ>
    792: static void PackInit_ComplexType(PetscSFLink link)
    793: {
    794:   link->d_Pack             = Pack<Type,BS,EQ>;
    795:   link->d_UnpackAndInsert  = Unpack<Type,BS,EQ>;
    796:   link->d_UnpackAndAdd     = UnpackAndOp<Type,Add<Type>   ,BS,EQ>;
    797:   link->d_UnpackAndMult    = UnpackAndOp<Type,Mult<Type>  ,BS,EQ>;
    798:   link->d_FetchAndAdd      = FetchAndOp <Type,Add<Type>   ,BS,EQ>;

    800:   link->d_ScatterAndInsert = ScatterAndInsert<Type,BS,EQ>;
    801:   link->d_ScatterAndAdd    = ScatterAndOp<Type,Add<Type>   ,BS,EQ>;
    802:   link->d_ScatterAndMult   = ScatterAndOp<Type,Mult<Type>  ,BS,EQ>;
    803:   link->d_FetchAndAddLocal = FetchAndOpLocal<Type,Add<Type>,BS,EQ>;

    805:   link->da_UnpackAndInsert = UnpackAndOp<Type,AtomicInsert<Type>,BS,EQ>;
    806:   link->da_UnpackAndAdd    = UnpackAndOp<Type,AtomicAdd<Type>,BS,EQ>;
    807:   link->da_UnpackAndMult   = NULL; /* Not implemented yet */
    808:   link->da_FetchAndAdd     = NULL; /* Return value of atomicAdd on complex is not atomic */

    810:   link->da_ScatterAndInsert = ScatterAndOp<Type,AtomicInsert<Type>,BS,EQ>;
    811:   link->da_ScatterAndAdd    = ScatterAndOp<Type,AtomicAdd<Type>,BS,EQ>;
    812: }
    813: #endif

    815: typedef signed char                      SignedChar;
    816: typedef unsigned char                    UnsignedChar;
    817: typedef struct {int a;      int b;     } PairInt;
    818: typedef struct {PetscInt a; PetscInt b;} PairPetscInt;

    820: template<typename Type>
    821: static void PackInit_PairType(PetscSFLink link)
    822: {
    823:   link->d_Pack            = Pack<Type,1,1>;
    824:   link->d_UnpackAndInsert = Unpack<Type,1,1>;
    825:   link->d_UnpackAndMaxloc = UnpackAndOp<Type,Maxloc<Type>,1,1>;
    826:   link->d_UnpackAndMinloc = UnpackAndOp<Type,Minloc<Type>,1,1>;

    828:   link->d_ScatterAndInsert = ScatterAndOp<Type,Insert<Type>,1,1>;
    829:   link->d_ScatterAndMaxloc = ScatterAndOp<Type,Maxloc<Type>,1,1>;
    830:   link->d_ScatterAndMinloc = ScatterAndOp<Type,Minloc<Type>,1,1>;
    831:   /* Atomics for pair types are not implemented yet */
    832: }

    834: template<typename Type,PetscInt BS,PetscInt EQ>
    835: static void PackInit_DumbType(PetscSFLink link)
    836: {
    837:   link->d_Pack             = Pack<Type,BS,EQ>;
    838:   link->d_UnpackAndInsert  = Unpack<Type,BS,EQ>;
    839:   link->d_ScatterAndInsert = ScatterAndInsert<Type,BS,EQ>;
    840:   /* Atomics for dumb types are not implemented yet */
    841: }

    843: /* Some device-specific utilities */
    844: static PetscErrorCode PetscSFLinkSyncDevice_CUDA(PetscSFLink link)
    845: {
    846:   cudaDeviceSynchronize();
    847:   return 0;
    848: }

    850: static PetscErrorCode PetscSFLinkSyncStream_CUDA(PetscSFLink link)
    851: {
    852:   cudaStreamSynchronize(link->stream);
    853:   return 0;
    854: }

    856: static PetscErrorCode PetscSFLinkMemcpy_CUDA(PetscSFLink link,PetscMemType dstmtype,void* dst,PetscMemType srcmtype,const void*src,size_t n)
    857: {
    858:   enum cudaMemcpyKind kinds[2][2] = {{cudaMemcpyHostToHost,cudaMemcpyHostToDevice},{cudaMemcpyDeviceToHost,cudaMemcpyDeviceToDevice}};

    860:   if (n) {
    861:     if (PetscMemTypeHost(dstmtype) && PetscMemTypeHost(srcmtype)) { /* Separate HostToHost so that pure-cpu code won't call cuda runtime */
    862:       PetscMemcpy(dst,src,n);
    863:     } else {
    864:       int stype = PetscMemTypeDevice(srcmtype) ? 1 : 0;
    865:       int dtype = PetscMemTypeDevice(dstmtype) ? 1 : 0;
    866:       cudaMemcpyAsync(dst,src,n,kinds[stype][dtype],link->stream);
    867:     }
    868:   }
    869:   return 0;
    870: }

    872: PetscErrorCode PetscSFMalloc_CUDA(PetscMemType mtype,size_t size,void** ptr)
    873: {
    874:   if (PetscMemTypeHost(mtype)) PetscMalloc(size,ptr);
    875:   else if (PetscMemTypeDevice(mtype)) {
    876:     PetscDeviceInitialize(PETSC_DEVICE_CUDA);
    877:     cudaMalloc(ptr,size);
    878:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Wrong PetscMemType %d", (int)mtype);
    879:   return 0;
    880: }

    882: PetscErrorCode PetscSFFree_CUDA(PetscMemType mtype,void* ptr)
    883: {
    884:   if (PetscMemTypeHost(mtype)) PetscFree(ptr);
    885:   else if (PetscMemTypeDevice(mtype)) cudaFree(ptr);
    886:   else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Wrong PetscMemType %d",(int)mtype);
    887:   return 0;
    888: }

    890: /* Destructor when the link uses MPI for communication on CUDA device */
    891: static PetscErrorCode PetscSFLinkDestroy_MPI_CUDA(PetscSF sf,PetscSFLink link)
    892: {
    893:   for (int i=PETSCSF_LOCAL; i<=PETSCSF_REMOTE; i++) {
    894:     cudaFree(link->rootbuf_alloc[i][PETSC_MEMTYPE_DEVICE]);
    895:     cudaFree(link->leafbuf_alloc[i][PETSC_MEMTYPE_DEVICE]);
    896:   }
    897:   return 0;
    898: }

    900: /* Some fields of link are initialized by PetscSFPackSetUp_Host. This routine only does what needed on device */
    901: PetscErrorCode PetscSFLinkSetUp_CUDA(PetscSF sf,PetscSFLink link,MPI_Datatype unit)
    902: {
    903:   PetscInt       nSignedChar=0,nUnsignedChar=0,nInt=0,nPetscInt=0,nPetscReal=0;
    904:   PetscBool      is2Int,is2PetscInt;
    905: #if defined(PETSC_HAVE_COMPLEX)
    906:   PetscInt       nPetscComplex=0;
    907: #endif

    909:   if (link->deviceinited) return 0;
    910:   MPIPetsc_Type_compare_contig(unit,MPI_SIGNED_CHAR,  &nSignedChar);
    911:   MPIPetsc_Type_compare_contig(unit,MPI_UNSIGNED_CHAR,&nUnsignedChar);
    912:   /* MPI_CHAR is treated below as a dumb type that does not support reduction according to MPI standard */
    913:   MPIPetsc_Type_compare_contig(unit,MPI_INT,  &nInt);
    914:   MPIPetsc_Type_compare_contig(unit,MPIU_INT, &nPetscInt);
    915:   MPIPetsc_Type_compare_contig(unit,MPIU_REAL,&nPetscReal);
    916: #if defined(PETSC_HAVE_COMPLEX)
    917:   MPIPetsc_Type_compare_contig(unit,MPIU_COMPLEX,&nPetscComplex);
    918: #endif
    919:   MPIPetsc_Type_compare(unit,MPI_2INT,&is2Int);
    920:   MPIPetsc_Type_compare(unit,MPIU_2INT,&is2PetscInt);

    922:   if (is2Int) {
    923:     PackInit_PairType<PairInt>(link);
    924:   } else if (is2PetscInt) { /* TODO: when is2PetscInt and nPetscInt=2, we don't know which path to take. The two paths support different ops. */
    925:     PackInit_PairType<PairPetscInt>(link);
    926:   } else if (nPetscReal) {
    927:    #if !defined(PETSC_HAVE_DEVICE)
    928:     if      (nPetscReal == 8) PackInit_RealType<PetscReal,8,1>(link); else if (nPetscReal%8 == 0) PackInit_RealType<PetscReal,8,0>(link);
    929:     else if (nPetscReal == 4) PackInit_RealType<PetscReal,4,1>(link); else if (nPetscReal%4 == 0) PackInit_RealType<PetscReal,4,0>(link);
    930:     else if (nPetscReal == 2) PackInit_RealType<PetscReal,2,1>(link); else if (nPetscReal%2 == 0) PackInit_RealType<PetscReal,2,0>(link);
    931:     else if (nPetscReal == 1) PackInit_RealType<PetscReal,1,1>(link); else if (nPetscReal%1 == 0)
    932:    #endif
    933:     PackInit_RealType<PetscReal,1,0>(link);
    934:   } else if (nPetscInt && sizeof(PetscInt) == sizeof(llint)) {
    935:    #if !defined(PETSC_HAVE_DEVICE)
    936:     if      (nPetscInt == 8) PackInit_IntegerType<llint,8,1>(link); else if (nPetscInt%8 == 0) PackInit_IntegerType<llint,8,0>(link);
    937:     else if (nPetscInt == 4) PackInit_IntegerType<llint,4,1>(link); else if (nPetscInt%4 == 0) PackInit_IntegerType<llint,4,0>(link);
    938:     else if (nPetscInt == 2) PackInit_IntegerType<llint,2,1>(link); else if (nPetscInt%2 == 0) PackInit_IntegerType<llint,2,0>(link);
    939:     else if (nPetscInt == 1) PackInit_IntegerType<llint,1,1>(link); else if (nPetscInt%1 == 0)
    940:    #endif
    941:     PackInit_IntegerType<llint,1,0>(link);
    942:   } else if (nInt) {
    943:    #if !defined(PETSC_HAVE_DEVICE)
    944:     if      (nInt == 8) PackInit_IntegerType<int,8,1>(link); else if (nInt%8 == 0) PackInit_IntegerType<int,8,0>(link);
    945:     else if (nInt == 4) PackInit_IntegerType<int,4,1>(link); else if (nInt%4 == 0) PackInit_IntegerType<int,4,0>(link);
    946:     else if (nInt == 2) PackInit_IntegerType<int,2,1>(link); else if (nInt%2 == 0) PackInit_IntegerType<int,2,0>(link);
    947:     else if (nInt == 1) PackInit_IntegerType<int,1,1>(link); else if (nInt%1 == 0)
    948:    #endif
    949:     PackInit_IntegerType<int,1,0>(link);
    950:   } else if (nSignedChar) {
    951:    #if !defined(PETSC_HAVE_DEVICE)
    952:     if      (nSignedChar == 8) PackInit_IntegerType<SignedChar,8,1>(link); else if (nSignedChar%8 == 0) PackInit_IntegerType<SignedChar,8,0>(link);
    953:     else if (nSignedChar == 4) PackInit_IntegerType<SignedChar,4,1>(link); else if (nSignedChar%4 == 0) PackInit_IntegerType<SignedChar,4,0>(link);
    954:     else if (nSignedChar == 2) PackInit_IntegerType<SignedChar,2,1>(link); else if (nSignedChar%2 == 0) PackInit_IntegerType<SignedChar,2,0>(link);
    955:     else if (nSignedChar == 1) PackInit_IntegerType<SignedChar,1,1>(link); else if (nSignedChar%1 == 0)
    956:    #endif
    957:     PackInit_IntegerType<SignedChar,1,0>(link);
    958:   }  else if (nUnsignedChar) {
    959:    #if !defined(PETSC_HAVE_DEVICE)
    960:     if      (nUnsignedChar == 8) PackInit_IntegerType<UnsignedChar,8,1>(link); else if (nUnsignedChar%8 == 0) PackInit_IntegerType<UnsignedChar,8,0>(link);
    961:     else if (nUnsignedChar == 4) PackInit_IntegerType<UnsignedChar,4,1>(link); else if (nUnsignedChar%4 == 0) PackInit_IntegerType<UnsignedChar,4,0>(link);
    962:     else if (nUnsignedChar == 2) PackInit_IntegerType<UnsignedChar,2,1>(link); else if (nUnsignedChar%2 == 0) PackInit_IntegerType<UnsignedChar,2,0>(link);
    963:     else if (nUnsignedChar == 1) PackInit_IntegerType<UnsignedChar,1,1>(link); else if (nUnsignedChar%1 == 0)
    964:    #endif
    965:     PackInit_IntegerType<UnsignedChar,1,0>(link);
    966: #if defined(PETSC_HAVE_COMPLEX)
    967:   } else if (nPetscComplex) {
    968:    #if !defined(PETSC_HAVE_DEVICE)
    969:     if      (nPetscComplex == 8) PackInit_ComplexType<PetscComplex,8,1>(link); else if (nPetscComplex%8 == 0) PackInit_ComplexType<PetscComplex,8,0>(link);
    970:     else if (nPetscComplex == 4) PackInit_ComplexType<PetscComplex,4,1>(link); else if (nPetscComplex%4 == 0) PackInit_ComplexType<PetscComplex,4,0>(link);
    971:     else if (nPetscComplex == 2) PackInit_ComplexType<PetscComplex,2,1>(link); else if (nPetscComplex%2 == 0) PackInit_ComplexType<PetscComplex,2,0>(link);
    972:     else if (nPetscComplex == 1) PackInit_ComplexType<PetscComplex,1,1>(link); else if (nPetscComplex%1 == 0)
    973:    #endif
    974:     PackInit_ComplexType<PetscComplex,1,0>(link);
    975: #endif
    976:   } else {
    977:     MPI_Aint lb,nbyte;
    978:     MPI_Type_get_extent(unit,&lb,&nbyte);
    980:     if (nbyte % sizeof(int)) { /* If the type size is not multiple of int */
    981:      #if !defined(PETSC_HAVE_DEVICE)
    982:       if      (nbyte == 4) PackInit_DumbType<char,4,1>(link); else if (nbyte%4 == 0) PackInit_DumbType<char,4,0>(link);
    983:       else if (nbyte == 2) PackInit_DumbType<char,2,1>(link); else if (nbyte%2 == 0) PackInit_DumbType<char,2,0>(link);
    984:       else if (nbyte == 1) PackInit_DumbType<char,1,1>(link); else if (nbyte%1 == 0)
    985:      #endif
    986:       PackInit_DumbType<char,1,0>(link);
    987:     } else {
    988:       nInt = nbyte / sizeof(int);
    989:      #if !defined(PETSC_HAVE_DEVICE)
    990:       if      (nInt == 8) PackInit_DumbType<int,8,1>(link); else if (nInt%8 == 0) PackInit_DumbType<int,8,0>(link);
    991:       else if (nInt == 4) PackInit_DumbType<int,4,1>(link); else if (nInt%4 == 0) PackInit_DumbType<int,4,0>(link);
    992:       else if (nInt == 2) PackInit_DumbType<int,2,1>(link); else if (nInt%2 == 0) PackInit_DumbType<int,2,0>(link);
    993:       else if (nInt == 1) PackInit_DumbType<int,1,1>(link); else if (nInt%1 == 0)
    994:      #endif
    995:       PackInit_DumbType<int,1,0>(link);
    996:     }
    997:   }

    999:   if (!sf->maxResidentThreadsPerGPU) { /* Not initialized */
    1000:     int                   device;
    1001:     struct cudaDeviceProp props;
    1002:     cudaGetDevice(&device);
    1003:     cudaGetDeviceProperties(&props,device);
    1004:     sf->maxResidentThreadsPerGPU = props.maxThreadsPerMultiProcessor*props.multiProcessorCount;
    1005:   }
    1006:   link->maxResidentThreadsPerGPU = sf->maxResidentThreadsPerGPU;

    1008:   link->stream             = PetscDefaultCudaStream;
    1009:   link->Destroy            = PetscSFLinkDestroy_MPI_CUDA;
    1010:   link->SyncDevice         = PetscSFLinkSyncDevice_CUDA;
    1011:   link->SyncStream         = PetscSFLinkSyncStream_CUDA;
    1012:   link->Memcpy             = PetscSFLinkMemcpy_CUDA;
    1013:   link->deviceinited       = PETSC_TRUE;
    1014:   return 0;
    1015: }