xref: /petsc/src/vec/is/sf/impls/basic/kokkos/sfkok.kokkos.cxx (revision d7cc930e14e615e9907267aaa472dd0ccceeab82)
1 #include <../src/vec/is/sf/impls/basic/sfpack.h>
2 
3 #include <Kokkos_Core.hpp>
4 
5 using DeviceExecutionSpace = Kokkos::DefaultExecutionSpace;
6 using DeviceMemorySpace    = typename DeviceExecutionSpace::memory_space;
7 using HostMemorySpace      = Kokkos::HostSpace;
8 
9 typedef Kokkos::View<char*,DeviceMemorySpace>       deviceBuffer_t;
10 typedef Kokkos::View<char*,HostMemorySpace>         HostBuffer_t;
11 
12 typedef Kokkos::View<const char*,DeviceMemorySpace> deviceConstBuffer_t;
13 typedef Kokkos::View<const char*,HostMemorySpace>   HostConstBuffer_t;
14 
15 /*====================================================================================*/
16 /*                             Regular operations                           */
17 /*====================================================================================*/
18 template<typename Type> struct Insert{KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x  = y;             return old;}};
19 template<typename Type> struct Add   {KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x += y;             return old;}};
20 template<typename Type> struct Mult  {KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x *= y;             return old;}};
21 template<typename Type> struct Min   {KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x  = PetscMin(x,y); return old;}};
22 template<typename Type> struct Max   {KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x  = PetscMax(x,y); return old;}};
23 template<typename Type> struct LAND  {KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x  = x && y;        return old;}};
24 template<typename Type> struct LOR   {KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x  = x || y;        return old;}};
25 template<typename Type> struct LXOR  {KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x  = !x != !y;      return old;}};
26 template<typename Type> struct BAND  {KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x  = x & y;         return old;}};
27 template<typename Type> struct BOR   {KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x  = x | y;         return old;}};
28 template<typename Type> struct BXOR  {KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {Type old = x; x  = x ^ y;         return old;}};
29 template<typename PairType> struct Minloc {
30   KOKKOS_INLINE_FUNCTION PairType operator()(PairType& x,PairType y) const {
31     PairType old = x;
32     if (y.first < x.first) x = y;
33     else if (y.first == x.first) x.second = PetscMin(x.second,y.second);
34     return old;
35   }
36 };
37 template<typename PairType> struct Maxloc {
38   KOKKOS_INLINE_FUNCTION PairType operator()(PairType& x,PairType y) const {
39     PairType old = x;
40     if (y.first > x.first) x = y;
41     else if (y.first == x.first) x.second = PetscMin(x.second,y.second); /* See MPI MAXLOC */
42     return old;
43   }
44 };
45 
46 /*====================================================================================*/
47 /*                             Atomic operations                            */
48 /*====================================================================================*/
49 template<typename Type> struct AtomicInsert  {KOKKOS_INLINE_FUNCTION void operator()(Type& x,Type y) const {Kokkos::atomic_assign(&x,y);}};
50 template<typename Type> struct AtomicAdd     {KOKKOS_INLINE_FUNCTION void operator()(Type& x,Type y) const {Kokkos::atomic_add(&x,y);}};
51 template<typename Type> struct AtomicBAND    {KOKKOS_INLINE_FUNCTION void operator()(Type& x,Type y) const {Kokkos::atomic_and(&x,y);}};
52 template<typename Type> struct AtomicBOR     {KOKKOS_INLINE_FUNCTION void operator()(Type& x,Type y) const {Kokkos::atomic_or (&x,y);}};
53 template<typename Type> struct AtomicBXOR    {KOKKOS_INLINE_FUNCTION void operator()(Type& x,Type y) const {Kokkos::atomic_fetch_xor(&x,y);}};
54 template<typename Type> struct AtomicLAND    {KOKKOS_INLINE_FUNCTION void operator()(Type& x,Type y) const {const Type zero=0,one=~0; Kokkos::atomic_and(&x,y?one:zero);}};
55 template<typename Type> struct AtomicLOR     {KOKKOS_INLINE_FUNCTION void operator()(Type& x,Type y) const {const Type zero=0,one=1;  Kokkos::atomic_or (&x,y?one:zero);}};
56 template<typename Type> struct AtomicMult    {KOKKOS_INLINE_FUNCTION void operator()(Type& x,Type y) const {Kokkos::atomic_fetch_mul(&x,y);}};
57 template<typename Type> struct AtomicMin     {KOKKOS_INLINE_FUNCTION void operator()(Type& x,Type y) const {Kokkos::atomic_fetch_min(&x,y);}};
58 template<typename Type> struct AtomicMax     {KOKKOS_INLINE_FUNCTION void operator()(Type& x,Type y) const {Kokkos::atomic_fetch_max(&x,y);}};
59 /* TODO: struct AtomicLXOR  */
60 template<typename Type> struct AtomicFetchAdd{KOKKOS_INLINE_FUNCTION Type operator()(Type& x,Type y) const {return Kokkos::atomic_fetch_add(&x,y);}};
61 
62 /* Map a thread id to an index in root/leaf space through a series of 3D subdomains. See PetscSFPackOpt. */
63 static KOKKOS_INLINE_FUNCTION PetscInt MapTidToIndex(const PetscInt *opt,PetscInt tid)
64 {
65   PetscInt        i,j,k,m,n,r;
66   const PetscInt  *offset,*start,*dx,*dy,*X,*Y;
67 
68   n      = opt[0];
69   offset = opt + 1;
70   start  = opt + n + 2;
71   dx     = opt + 2*n + 2;
72   dy     = opt + 3*n + 2;
73   X      = opt + 5*n + 2;
74   Y      = opt + 6*n + 2;
75   for (r=0; r<n; r++) {if (tid < offset[r+1]) break;}
76   m = (tid - offset[r]);
77   k = m/(dx[r]*dy[r]);
78   j = (m - k*dx[r]*dy[r])/dx[r];
79   i = m - k*dx[r]*dy[r] - j*dx[r];
80 
81   return (start[r] + k*X[r]*Y[r] + j*X[r] + i);
82 }
83 
84 /*====================================================================================*/
85 /*  Wrappers for Pack/Unpack/Scatter kernels. Function pointers are stored in 'link'         */
86 /*====================================================================================*/
87 
88 /* Suppose user calls PetscSFReduce(sf,unit,...) and <unit> is an MPI data type made of 16 PetscReals, then
89    <Type> is PetscReal, which is the primitive type we operate on.
90    <bs>   is 16, which says <unit> contains 16 primitive types.
91    <BS>   is 8, which is the maximal SIMD width we will try to vectorize operations on <unit>.
92    <EQ>   is 0, which is (bs == BS ? 1 : 0)
93 
94   If instead, <unit> has 8 PetscReals, then bs=8, BS=8, EQ=1, rendering MBS below to a compile time constant.
95   For the common case in VecScatter, bs=1, BS=1, EQ=1, MBS=1, the inner for-loops below will be totally unrolled.
96 */
97 template<typename Type,PetscInt BS,PetscInt EQ>
98 static PetscErrorCode Pack(PetscSFLink link,PetscInt count,PetscInt start,PetscSFPackOpt opt,const PetscInt *idx,const void *data_,void *buf_)
99 {
100   const PetscInt          *iopt = opt ? opt->array : NULL;
101   const PetscInt          M = EQ ? 1 : link->bs/BS, MBS=M*BS; /* If EQ, then MBS will be a compile-time const */
102   const Type              *data = static_cast<const Type*>(data_);
103   Type                    *buf = static_cast<Type*>(buf_);
104   DeviceExecutionSpace&   exec = *static_cast<DeviceExecutionSpace*>(link->sptr);
105 
106   PetscFunctionBegin;
107   Kokkos::parallel_for(Kokkos::RangePolicy<DeviceExecutionSpace>(exec,0,count),KOKKOS_LAMBDA(PetscInt tid) {
108     /* iopt != NULL ==> idx == NULL, i.e., the indices have patterns but not contiguous;
109        iopt == NULL && idx == NULL ==> the indices are contiguous;
110      */
111     PetscInt t = (iopt? MapTidToIndex(iopt,tid) : (idx? idx[tid] : start+tid))*MBS;
112     PetscInt s = tid*MBS;
113     for (int i=0; i<MBS; i++) buf[s+i] = data[t+i];
114   });
115   PetscFunctionReturn(0);
116 }
117 
118 template<typename Type,class Op,PetscInt BS,PetscInt EQ>
119 static PetscErrorCode UnpackAndOp(PetscSFLink link,PetscInt count,PetscInt start,PetscSFPackOpt opt,const PetscInt *idx,void *data_,const void *buf_)
120 {
121   Op                      op;
122   const PetscInt          *iopt = opt ? opt->array : NULL;
123   const PetscInt          M = EQ ? 1 : link->bs/BS, MBS=M*BS;
124   Type                    *data = static_cast<Type*>(data_);
125   const Type              *buf = static_cast<const Type*>(buf_);
126   DeviceExecutionSpace&   exec = *static_cast<DeviceExecutionSpace*>(link->sptr);
127 
128   PetscFunctionBegin;
129   Kokkos::parallel_for(Kokkos::RangePolicy<DeviceExecutionSpace>(exec,0,count),KOKKOS_LAMBDA(PetscInt tid) {
130     PetscInt t = (iopt? MapTidToIndex(iopt,tid) : (idx? idx[tid] : start+tid))*MBS;
131     PetscInt s = tid*MBS;
132     for (int i=0; i<MBS; i++) op(data[t+i],buf[s+i]);
133   });
134   PetscFunctionReturn(0);
135 }
136 
137 template<typename Type,class Op,PetscInt BS,PetscInt EQ>
138 static PetscErrorCode FetchAndOp(PetscSFLink link,PetscInt count,PetscInt start,PetscSFPackOpt opt,const PetscInt *idx,void *data,void *buf)
139 {
140   Op                      op;
141   const PetscInt          *ropt = opt ? opt->array : NULL;
142   const PetscInt          M = EQ ? 1 : link->bs/BS, MBS=M*BS;
143   Type                    *rootdata = static_cast<Type*>(data),*leafbuf=static_cast<Type*>(buf);
144   DeviceExecutionSpace&   exec = *static_cast<DeviceExecutionSpace*>(link->sptr);
145 
146   PetscFunctionBegin;
147   Kokkos::parallel_for(Kokkos::RangePolicy<DeviceExecutionSpace>(exec,0,count),KOKKOS_LAMBDA(PetscInt tid) {
148     PetscInt r = (ropt? MapTidToIndex(ropt,tid) : (idx? idx[tid] : start+tid))*MBS;
149     PetscInt l = tid*MBS;
150     for (int i=0; i<MBS; i++) leafbuf[l+i] = op(rootdata[r+i],leafbuf[l+i]);
151   });
152   PetscFunctionReturn(0);
153 }
154 
155 template<typename Type,class Op,PetscInt BS,PetscInt EQ>
156 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_)
157 {
158   PetscInt                srcx=0,srcy=0,srcX=0,srcY=0,dstx=0,dsty=0,dstX=0,dstY=0;
159   const PetscInt          M = (EQ) ? 1 : link->bs/BS, MBS=M*BS;
160   const Type              *src = static_cast<const Type*>(src_);
161   Type                    *dst = static_cast<Type*>(dst_);
162   DeviceExecutionSpace&   exec = *static_cast<DeviceExecutionSpace*>(link->sptr);
163 
164   PetscFunctionBegin;
165   /* 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 */
166   if (srcOpt)       {srcx = srcOpt->dx[0]; srcy = srcOpt->dy[0]; srcX = srcOpt->X[0]; srcY = srcOpt->Y[0]; srcStart = srcOpt->start[0]; srcIdx = NULL;}
167   else if (!srcIdx) {srcx = srcX = count; srcy = srcY = 1;}
168 
169   if (dstOpt)       {dstx = dstOpt->dx[0]; dsty = dstOpt->dy[0]; dstX = dstOpt->X[0]; dstY = dstOpt->Y[0]; dstStart = dstOpt->start[0]; dstIdx = NULL;}
170   else if (!dstIdx) {dstx = dstX = count; dsty = dstY = 1;}
171 
172   Kokkos::parallel_for(Kokkos::RangePolicy<DeviceExecutionSpace>(exec,0,count),KOKKOS_LAMBDA(PetscInt tid) {
173     PetscInt i,j,k,s,t;
174     Op       op;
175     if (!srcIdx) { /* src is in 3D */
176       k = tid/(srcx*srcy);
177       j = (tid - k*srcx*srcy)/srcx;
178       i = tid - k*srcx*srcy - j*srcx;
179       s = srcStart + k*srcX*srcY + j*srcX + i;
180     } else { /* src is contiguous */
181       s = srcIdx[tid];
182     }
183 
184     if (!dstIdx) { /* 3D */
185       k = tid/(dstx*dsty);
186       j = (tid - k*dstx*dsty)/dstx;
187       i = tid - k*dstx*dsty - j*dstx;
188       t = dstStart + k*dstX*dstY + j*dstX + i;
189     } else { /* contiguous */
190       t = dstIdx[tid];
191     }
192 
193     s *= MBS;
194     t *= MBS;
195     for (i=0; i<MBS; i++) op(dst[t+i],src[s+i]);
196   });
197   PetscFunctionReturn(0);
198 }
199 
200 /* Specialization for Insert since we may use memcpy */
201 template<typename Type,PetscInt BS,PetscInt EQ>
202 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_)
203 {
204   PetscErrorCode          ierr;
205   const Type              *src = static_cast<const Type*>(src_);
206   Type                    *dst = static_cast<Type*>(dst_);
207   DeviceExecutionSpace&   exec = *static_cast<DeviceExecutionSpace*>(link->sptr);
208 
209   PetscFunctionBegin;
210   if (!count) PetscFunctionReturn(0);
211   /*src and dst are contiguous */
212   if ((!srcOpt && !srcIdx) && (!dstOpt && !dstIdx) && src != dst) {
213     size_t sz = count*link->unitbytes;
214     deviceBuffer_t      dbuf(reinterpret_cast<char*>(dst+dstStart*link->bs),sz);
215     deviceConstBuffer_t sbuf(reinterpret_cast<const char*>(src+srcStart*link->bs),sz);
216     Kokkos::deep_copy(exec,dbuf,sbuf);
217   } else {
218     ierr = ScatterAndOp<Type,Insert<Type>,BS,EQ>(link,count,srcStart,srcOpt,srcIdx,src,dstStart,dstOpt,dstIdx,dst);CHKERRQ(ierr);
219   }
220   PetscFunctionReturn(0);
221 }
222 
223 template<typename Type,class Op,PetscInt BS,PetscInt EQ>
224 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_)
225 {
226   Op                      op;
227   const PetscInt          M = (EQ) ? 1 : link->bs/BS, MBS = M*BS;
228   const PetscInt          *ropt = rootopt ? rootopt->array : NULL;
229   const PetscInt          *lopt = leafopt ? leafopt->array : NULL;
230   Type                    *rootdata = static_cast<Type*>(rootdata_),*leafupdate = static_cast<Type*>(leafupdate_);
231   const Type              *leafdata = static_cast<const Type*>(leafdata_);
232   DeviceExecutionSpace&   exec = *static_cast<DeviceExecutionSpace*>(link->sptr);
233 
234   PetscFunctionBegin;
235   Kokkos::parallel_for(Kokkos::RangePolicy<DeviceExecutionSpace>(exec,0,count),KOKKOS_LAMBDA(PetscInt tid) {
236     PetscInt r = (ropt? MapTidToIndex(ropt,tid) : (rootidx? rootidx[tid] : rootstart+tid))*MBS;
237     PetscInt l = (lopt? MapTidToIndex(lopt,tid) : (leafidx? leafidx[tid] : leafstart+tid))*MBS;
238     for (int i=0; i<MBS; i++) leafupdate[l+i] = op(rootdata[r+i],leafdata[l+i]);
239   });
240   PetscFunctionReturn(0);
241 }
242 
243 /*====================================================================================*/
244 /*  Init various types and instantiate pack/unpack function pointers                  */
245 /*====================================================================================*/
246 template<typename Type,PetscInt BS,PetscInt EQ>
247 static void PackInit_RealType(PetscSFLink link)
248 {
249   /* Pack/unpack for remote communication */
250   link->d_Pack              = Pack<Type,BS,EQ>;
251   link->d_UnpackAndInsert   = UnpackAndOp<Type,Insert<Type>,BS,EQ>;
252   link->d_UnpackAndAdd      = UnpackAndOp<Type,Add<Type>   ,BS,EQ>;
253   link->d_UnpackAndMult     = UnpackAndOp<Type,Mult<Type>  ,BS,EQ>;
254   link->d_UnpackAndMin      = UnpackAndOp<Type,Min<Type>   ,BS,EQ>;
255   link->d_UnpackAndMax      = UnpackAndOp<Type,Max<Type>   ,BS,EQ>;
256   link->d_FetchAndAdd       = FetchAndOp <Type,Add<Type>   ,BS,EQ>;
257   /* Scatter for local communication */
258   link->d_ScatterAndInsert  = ScatterAndInsert<Type,BS,EQ>; /* Has special optimizations */
259   link->d_ScatterAndAdd     = ScatterAndOp<Type,Add<Type>    ,BS,EQ>;
260   link->d_ScatterAndMult    = ScatterAndOp<Type,Mult<Type>   ,BS,EQ>;
261   link->d_ScatterAndMin     = ScatterAndOp<Type,Min<Type>    ,BS,EQ>;
262   link->d_ScatterAndMax     = ScatterAndOp<Type,Max<Type>    ,BS,EQ>;
263   link->d_FetchAndAddLocal  = FetchAndOpLocal<Type,Add <Type>,BS,EQ>;
264   /* Atomic versions when there are data-race possibilities */
265   link->da_UnpackAndInsert  = UnpackAndOp<Type,AtomicInsert<Type>  ,BS,EQ>;
266   link->da_UnpackAndAdd     = UnpackAndOp<Type,AtomicAdd<Type>     ,BS,EQ>;
267   link->da_UnpackAndMult    = UnpackAndOp<Type,AtomicMult<Type>    ,BS,EQ>;
268   link->da_UnpackAndMin     = UnpackAndOp<Type,AtomicMin<Type>     ,BS,EQ>;
269   link->da_UnpackAndMax     = UnpackAndOp<Type,AtomicMax<Type>     ,BS,EQ>;
270   link->da_FetchAndAdd      = FetchAndOp <Type,AtomicFetchAdd<Type>,BS,EQ>;
271 
272   link->da_ScatterAndInsert = ScatterAndOp<Type,AtomicInsert<Type>,BS,EQ>;
273   link->da_ScatterAndAdd    = ScatterAndOp<Type,AtomicAdd<Type>   ,BS,EQ>;
274   link->da_ScatterAndMult   = ScatterAndOp<Type,AtomicMult<Type>  ,BS,EQ>;
275   link->da_ScatterAndMin    = ScatterAndOp<Type,AtomicMin<Type>   ,BS,EQ>;
276   link->da_ScatterAndMax    = ScatterAndOp<Type,AtomicMax<Type>   ,BS,EQ>;
277   link->da_FetchAndAddLocal = FetchAndOpLocal<Type,AtomicFetchAdd<Type>,BS,EQ>;
278 }
279 
280 template<typename Type,PetscInt BS,PetscInt EQ>
281 static void PackInit_IntegerType(PetscSFLink link)
282 {
283   link->d_Pack              = Pack<Type,BS,EQ>;
284   link->d_UnpackAndInsert   = UnpackAndOp<Type,Insert<Type> ,BS,EQ>;
285   link->d_UnpackAndAdd      = UnpackAndOp<Type,Add<Type>    ,BS,EQ>;
286   link->d_UnpackAndMult     = UnpackAndOp<Type,Mult<Type>   ,BS,EQ>;
287   link->d_UnpackAndMin      = UnpackAndOp<Type,Min<Type>    ,BS,EQ>;
288   link->d_UnpackAndMax      = UnpackAndOp<Type,Max<Type>    ,BS,EQ>;
289   link->d_UnpackAndLAND     = UnpackAndOp<Type,LAND<Type>   ,BS,EQ>;
290   link->d_UnpackAndLOR      = UnpackAndOp<Type,LOR<Type>    ,BS,EQ>;
291   link->d_UnpackAndLXOR     = UnpackAndOp<Type,LXOR<Type>   ,BS,EQ>;
292   link->d_UnpackAndBAND     = UnpackAndOp<Type,BAND<Type>   ,BS,EQ>;
293   link->d_UnpackAndBOR      = UnpackAndOp<Type,BOR<Type>    ,BS,EQ>;
294   link->d_UnpackAndBXOR     = UnpackAndOp<Type,BXOR<Type>   ,BS,EQ>;
295   link->d_FetchAndAdd       = FetchAndOp <Type,Add<Type>    ,BS,EQ>;
296 
297   link->d_ScatterAndInsert  = ScatterAndInsert<Type,BS,EQ>;
298   link->d_ScatterAndAdd     = ScatterAndOp<Type,Add<Type>   ,BS,EQ>;
299   link->d_ScatterAndMult    = ScatterAndOp<Type,Mult<Type>  ,BS,EQ>;
300   link->d_ScatterAndMin     = ScatterAndOp<Type,Min<Type>   ,BS,EQ>;
301   link->d_ScatterAndMax     = ScatterAndOp<Type,Max<Type>   ,BS,EQ>;
302   link->d_ScatterAndLAND    = ScatterAndOp<Type,LAND<Type>  ,BS,EQ>;
303   link->d_ScatterAndLOR     = ScatterAndOp<Type,LOR<Type>   ,BS,EQ>;
304   link->d_ScatterAndLXOR    = ScatterAndOp<Type,LXOR<Type>  ,BS,EQ>;
305   link->d_ScatterAndBAND    = ScatterAndOp<Type,BAND<Type>  ,BS,EQ>;
306   link->d_ScatterAndBOR     = ScatterAndOp<Type,BOR<Type>   ,BS,EQ>;
307   link->d_ScatterAndBXOR    = ScatterAndOp<Type,BXOR<Type>  ,BS,EQ>;
308   link->d_FetchAndAddLocal  = FetchAndOpLocal<Type,Add<Type>,BS,EQ>;
309 
310   link->da_UnpackAndInsert  = UnpackAndOp<Type,AtomicInsert<Type>,BS,EQ>;
311   link->da_UnpackAndAdd     = UnpackAndOp<Type,AtomicAdd<Type>   ,BS,EQ>;
312   link->da_UnpackAndMult    = UnpackAndOp<Type,AtomicMult<Type>  ,BS,EQ>;
313   link->da_UnpackAndMin     = UnpackAndOp<Type,AtomicMin<Type>   ,BS,EQ>;
314   link->da_UnpackAndMax     = UnpackAndOp<Type,AtomicMax<Type>   ,BS,EQ>;
315   link->da_UnpackAndLAND    = UnpackAndOp<Type,AtomicLAND<Type>  ,BS,EQ>;
316   link->da_UnpackAndLOR     = UnpackAndOp<Type,AtomicLOR<Type>   ,BS,EQ>;
317   link->da_UnpackAndBAND    = UnpackAndOp<Type,AtomicBAND<Type>  ,BS,EQ>;
318   link->da_UnpackAndBOR     = UnpackAndOp<Type,AtomicBOR<Type>   ,BS,EQ>;
319   link->da_UnpackAndBXOR    = UnpackAndOp<Type,AtomicBXOR<Type>  ,BS,EQ>;
320   link->da_FetchAndAdd      = FetchAndOp <Type,AtomicFetchAdd<Type>,BS,EQ>;
321 
322   link->da_ScatterAndInsert = ScatterAndOp<Type,AtomicInsert<Type>,BS,EQ>;
323   link->da_ScatterAndAdd    = ScatterAndOp<Type,AtomicAdd<Type>   ,BS,EQ>;
324   link->da_ScatterAndMult   = ScatterAndOp<Type,AtomicMult<Type>  ,BS,EQ>;
325   link->da_ScatterAndMin    = ScatterAndOp<Type,AtomicMin<Type>   ,BS,EQ>;
326   link->da_ScatterAndMax    = ScatterAndOp<Type,AtomicMax<Type>   ,BS,EQ>;
327   link->da_ScatterAndLAND   = ScatterAndOp<Type,AtomicLAND<Type>  ,BS,EQ>;
328   link->da_ScatterAndLOR    = ScatterAndOp<Type,AtomicLOR<Type>   ,BS,EQ>;
329   link->da_ScatterAndBAND   = ScatterAndOp<Type,AtomicBAND<Type>  ,BS,EQ>;
330   link->da_ScatterAndBOR    = ScatterAndOp<Type,AtomicBOR<Type>   ,BS,EQ>;
331   link->da_ScatterAndBXOR   = ScatterAndOp<Type,AtomicBXOR<Type>  ,BS,EQ>;
332   link->da_FetchAndAddLocal = FetchAndOpLocal<Type,AtomicFetchAdd<Type>,BS,EQ>;
333 }
334 
335 #if defined(PETSC_HAVE_COMPLEX)
336 template<typename Type,PetscInt BS,PetscInt EQ>
337 static void PackInit_ComplexType(PetscSFLink link)
338 {
339   link->d_Pack             = Pack<Type,BS,EQ>;
340   link->d_UnpackAndInsert  = UnpackAndOp<Type,Insert<Type>,BS,EQ>;
341   link->d_UnpackAndAdd     = UnpackAndOp<Type,Add<Type>   ,BS,EQ>;
342   link->d_UnpackAndMult    = UnpackAndOp<Type,Mult<Type>  ,BS,EQ>;
343   link->d_FetchAndAdd      = FetchAndOp <Type,Add<Type>   ,BS,EQ>;
344 
345   link->d_ScatterAndInsert = ScatterAndInsert<Type,BS,EQ>;
346   link->d_ScatterAndAdd    = ScatterAndOp<Type,Add<Type>   ,BS,EQ>;
347   link->d_ScatterAndMult   = ScatterAndOp<Type,Mult<Type>  ,BS,EQ>;
348   link->d_FetchAndAddLocal = FetchAndOpLocal<Type,Add<Type>,BS,EQ>;
349 
350   link->da_UnpackAndInsert = UnpackAndOp<Type,AtomicInsert<Type> ,BS,EQ>;
351   link->da_UnpackAndAdd    = UnpackAndOp<Type,AtomicAdd<Type>    ,BS,EQ>;
352   link->da_UnpackAndMult   = UnpackAndOp<Type,AtomicMult<Type>   ,BS,EQ>;
353   link->da_FetchAndAdd     = FetchAndOp<Type,AtomicFetchAdd<Type>,BS,EQ>;
354 
355   link->da_ScatterAndInsert = ScatterAndOp<Type,AtomicInsert<Type>,BS,EQ>;
356   link->da_ScatterAndAdd    = ScatterAndOp<Type,AtomicAdd<Type>   ,BS,EQ>;
357   link->da_ScatterAndMult   = ScatterAndOp<Type,AtomicMult<Type>  ,BS,EQ>;
358   link->da_FetchAndAddLocal = FetchAndOpLocal<Type,AtomicFetchAdd<Type>,BS,EQ>;
359 }
360 #endif
361 
362 template<typename Type>
363 static void PackInit_PairType(PetscSFLink link)
364 {
365   link->d_Pack             = Pack<Type,1,1>;
366   link->d_UnpackAndInsert  = UnpackAndOp<Type,Insert<Type>,1,1>;
367   link->d_UnpackAndMaxloc  = UnpackAndOp<Type,Maxloc<Type>,1,1>;
368   link->d_UnpackAndMinloc  = UnpackAndOp<Type,Minloc<Type>,1,1>;
369 
370   link->d_ScatterAndInsert = ScatterAndOp<Type,Insert<Type>,1,1>;
371   link->d_ScatterAndMaxloc = ScatterAndOp<Type,Maxloc<Type>,1,1>;
372   link->d_ScatterAndMinloc = ScatterAndOp<Type,Minloc<Type>,1,1>;
373   /* Atomics for pair types are not implemented yet */
374 }
375 
376 template<typename Type,PetscInt BS,PetscInt EQ>
377 static void PackInit_DumbType(PetscSFLink link)
378 {
379   link->d_Pack             = Pack<Type,BS,EQ>;
380   link->d_UnpackAndInsert  = UnpackAndOp<Type,Insert<Type>,BS,EQ>;
381   link->d_ScatterAndInsert = ScatterAndInsert<Type,BS,EQ>;
382   /* Atomics for dumb types are not implemented yet */
383 }
384 
385 static PetscErrorCode PetscSFLinkDestroy_Kokkos(PetscSFLink link)
386 {
387   PetscFunctionBegin;
388   delete static_cast<DeviceExecutionSpace*>(link->sptr);
389   PetscFunctionReturn(0);
390 }
391 
392 /* Some device-specific utilities */
393 static PetscErrorCode PetscSFLinkSyncDevice_Kokkos(PetscSFLink link)
394 {
395   PetscFunctionBegin;
396   Kokkos::fence();
397   PetscFunctionReturn(0);
398 }
399 
400 static PetscErrorCode PetscSFLinkSyncStream_Kokkos(PetscSFLink link)
401 {
402   DeviceExecutionSpace&  exec = *static_cast<DeviceExecutionSpace*>(link->sptr);
403   PetscFunctionBegin;
404   exec.fence();
405   PetscFunctionReturn(0);
406 }
407 
408 static PetscErrorCode PetscSFLinkMemcpy_Kokkos(PetscSFLink link,PetscMemType dstmtype,void* dst,PetscMemType srcmtype,const void*src,size_t n)
409 {
410   DeviceExecutionSpace&  exec = *static_cast<DeviceExecutionSpace*>(link->sptr);
411 
412   PetscFunctionBegin;
413   if (!n) PetscFunctionReturn(0);
414   if (dstmtype == PETSC_MEMTYPE_HOST && srcmtype == PETSC_MEMTYPE_HOST) {
415     PetscErrorCode ierr = PetscMemcpy(dst,src,n);CHKERRQ(ierr);
416   } else {
417     if (dstmtype == PETSC_MEMTYPE_DEVICE && srcmtype == PETSC_MEMTYPE_HOST) {
418       deviceBuffer_t       dbuf(static_cast<char*>(dst),n);
419       HostConstBuffer_t    sbuf(static_cast<const char*>(src),n);
420       Kokkos::deep_copy(exec,dbuf,sbuf);
421       PetscErrorCode ierr = PetscLogCpuToGpu(n);CHKERRQ(ierr);
422     } else if (dstmtype == PETSC_MEMTYPE_HOST && srcmtype == PETSC_MEMTYPE_DEVICE) {
423       HostBuffer_t         dbuf(static_cast<char*>(dst),n);
424       deviceConstBuffer_t  sbuf(static_cast<const char*>(src),n);
425       Kokkos::deep_copy(exec,dbuf,sbuf);
426       PetscErrorCode ierr = PetscLogGpuToCpu(n);CHKERRQ(ierr);
427     } else if (dstmtype == PETSC_MEMTYPE_DEVICE && srcmtype == PETSC_MEMTYPE_DEVICE) {
428       deviceBuffer_t       dbuf(static_cast<char*>(dst),n);
429       deviceConstBuffer_t  sbuf(static_cast<const char*>(src),n);
430       Kokkos::deep_copy(exec,dbuf,sbuf);
431     }
432   }
433   PetscFunctionReturn(0);
434 }
435 
436 PetscErrorCode PetscSFMalloc_Kokkos(PetscMemType mtype,size_t size,void** ptr)
437 {
438   PetscFunctionBegin;
439   if (mtype == PETSC_MEMTYPE_HOST) {PetscErrorCode ierr = PetscMalloc(size,ptr);CHKERRQ(ierr);}
440   else if (mtype == PETSC_MEMTYPE_DEVICE) {*ptr = Kokkos::kokkos_malloc<DeviceMemorySpace>(size);}
441   else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Wrong PetscMemType %d", (int)mtype);
442   PetscFunctionReturn(0);
443 }
444 
445 PetscErrorCode PetscSFFree_Kokkos(PetscMemType mtype,void* ptr)
446 {
447   PetscFunctionBegin;
448   if (mtype == PETSC_MEMTYPE_HOST) {PetscErrorCode ierr = PetscFree(ptr);CHKERRQ(ierr);}
449   else if (mtype == PETSC_MEMTYPE_DEVICE) {Kokkos::kokkos_free<DeviceMemorySpace>(ptr);}
450   else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Wrong PetscMemType %d",(int)mtype);
451   PetscFunctionReturn(0);
452 }
453 
454 /*====================================================================================*/
455 /*                Main driver to init MPI datatype on device                          */
456 /*====================================================================================*/
457 
458 /* Some fields of link are initialized by PetscSFPackSetUp_Host. This routine only does what needed on device */
459 PetscErrorCode PetscSFLinkSetUp_Kokkos(PetscSF sf,PetscSFLink link,MPI_Datatype unit)
460 {
461   PetscErrorCode ierr;
462   PetscInt       nSignedChar=0,nUnsignedChar=0,nInt=0,nPetscInt=0,nPetscReal=0;
463   PetscBool      is2Int,is2PetscInt;
464 #if defined(PETSC_HAVE_COMPLEX)
465   PetscInt       nPetscComplex=0;
466 #endif
467 
468   PetscFunctionBegin;
469   if (link->deviceinited) PetscFunctionReturn(0);
470   ierr = MPIPetsc_Type_compare_contig(unit,MPI_SIGNED_CHAR,  &nSignedChar);CHKERRQ(ierr);
471   ierr = MPIPetsc_Type_compare_contig(unit,MPI_UNSIGNED_CHAR,&nUnsignedChar);CHKERRQ(ierr);
472   /* MPI_CHAR is treated below as a dumb type that does not support reduction according to MPI standard */
473   ierr = MPIPetsc_Type_compare_contig(unit,MPI_INT,  &nInt);CHKERRQ(ierr);
474   ierr = MPIPetsc_Type_compare_contig(unit,MPIU_INT, &nPetscInt);CHKERRQ(ierr);
475   ierr = MPIPetsc_Type_compare_contig(unit,MPIU_REAL,&nPetscReal);CHKERRQ(ierr);
476 #if defined(PETSC_HAVE_COMPLEX)
477   ierr = MPIPetsc_Type_compare_contig(unit,MPIU_COMPLEX,&nPetscComplex);CHKERRQ(ierr);
478 #endif
479   ierr = MPIPetsc_Type_compare(unit,MPI_2INT,&is2Int);CHKERRQ(ierr);
480   ierr = MPIPetsc_Type_compare(unit,MPIU_2INT,&is2PetscInt);CHKERRQ(ierr);
481 
482   if (is2Int) {
483     PackInit_PairType<Kokkos::pair<int,int>>(link);
484   } else if (is2PetscInt) { /* TODO: when is2PetscInt and nPetscInt=2, we don't know which path to take. The two paths support different ops. */
485     PackInit_PairType<Kokkos::pair<PetscInt,PetscInt>>(link);
486   } else if (nPetscReal) {
487     if      (nPetscReal == 8) PackInit_RealType<PetscReal,8,1>(link); else if (nPetscReal%8 == 0) PackInit_RealType<PetscReal,8,0>(link);
488     else if (nPetscReal == 4) PackInit_RealType<PetscReal,4,1>(link); else if (nPetscReal%4 == 0) PackInit_RealType<PetscReal,4,0>(link);
489     else if (nPetscReal == 2) PackInit_RealType<PetscReal,2,1>(link); else if (nPetscReal%2 == 0) PackInit_RealType<PetscReal,2,0>(link);
490     else if (nPetscReal == 1) PackInit_RealType<PetscReal,1,1>(link); else if (nPetscReal%1 == 0) PackInit_RealType<PetscReal,1,0>(link);
491   } else if (nPetscInt) {
492     if      (nPetscInt == 8) PackInit_IntegerType<PetscInt,8,1>(link); else if (nPetscInt%8 == 0) PackInit_IntegerType<PetscInt,8,0>(link);
493     else if (nPetscInt == 4) PackInit_IntegerType<PetscInt,4,1>(link); else if (nPetscInt%4 == 0) PackInit_IntegerType<PetscInt,4,0>(link);
494     else if (nPetscInt == 2) PackInit_IntegerType<PetscInt,2,1>(link); else if (nPetscInt%2 == 0) PackInit_IntegerType<PetscInt,2,0>(link);
495     else if (nPetscInt == 1) PackInit_IntegerType<PetscInt,1,1>(link); else if (nPetscInt%1 == 0) PackInit_IntegerType<PetscInt,1,0>(link);
496 #if defined(PETSC_USE_64BIT_INDICES)
497   } else if (nInt) {
498     if      (nInt == 8) PackInit_IntegerType<int,8,1>(link); else if (nInt%8 == 0) PackInit_IntegerType<int,8,0>(link);
499     else if (nInt == 4) PackInit_IntegerType<int,4,1>(link); else if (nInt%4 == 0) PackInit_IntegerType<int,4,0>(link);
500     else if (nInt == 2) PackInit_IntegerType<int,2,1>(link); else if (nInt%2 == 0) PackInit_IntegerType<int,2,0>(link);
501     else if (nInt == 1) PackInit_IntegerType<int,1,1>(link); else if (nInt%1 == 0) PackInit_IntegerType<int,1,0>(link);
502 #endif
503   } else if (nSignedChar) {
504     if      (nSignedChar == 8) PackInit_IntegerType<char,8,1>(link); else if (nSignedChar%8 == 0) PackInit_IntegerType<char,8,0>(link);
505     else if (nSignedChar == 4) PackInit_IntegerType<char,4,1>(link); else if (nSignedChar%4 == 0) PackInit_IntegerType<char,4,0>(link);
506     else if (nSignedChar == 2) PackInit_IntegerType<char,2,1>(link); else if (nSignedChar%2 == 0) PackInit_IntegerType<char,2,0>(link);
507     else if (nSignedChar == 1) PackInit_IntegerType<char,1,1>(link); else if (nSignedChar%1 == 0) PackInit_IntegerType<char,1,0>(link);
508   }  else if (nUnsignedChar) {
509     if      (nUnsignedChar == 8) PackInit_IntegerType<unsigned char,8,1>(link); else if (nUnsignedChar%8 == 0) PackInit_IntegerType<unsigned char,8,0>(link);
510     else if (nUnsignedChar == 4) PackInit_IntegerType<unsigned char,4,1>(link); else if (nUnsignedChar%4 == 0) PackInit_IntegerType<unsigned char,4,0>(link);
511     else if (nUnsignedChar == 2) PackInit_IntegerType<unsigned char,2,1>(link); else if (nUnsignedChar%2 == 0) PackInit_IntegerType<unsigned char,2,0>(link);
512     else if (nUnsignedChar == 1) PackInit_IntegerType<unsigned char,1,1>(link); else if (nUnsignedChar%1 == 0) PackInit_IntegerType<unsigned char,1,0>(link);
513 #if defined(PETSC_HAVE_COMPLEX)
514   } else if (nPetscComplex) {
515     if      (nPetscComplex == 8) PackInit_ComplexType<Kokkos::complex<PetscReal>,8,1>(link); else if (nPetscComplex%8 == 0) PackInit_ComplexType<Kokkos::complex<PetscReal>,8,0>(link);
516     else if (nPetscComplex == 4) PackInit_ComplexType<Kokkos::complex<PetscReal>,4,1>(link); else if (nPetscComplex%4 == 0) PackInit_ComplexType<Kokkos::complex<PetscReal>,4,0>(link);
517     else if (nPetscComplex == 2) PackInit_ComplexType<Kokkos::complex<PetscReal>,2,1>(link); else if (nPetscComplex%2 == 0) PackInit_ComplexType<Kokkos::complex<PetscReal>,2,0>(link);
518     else if (nPetscComplex == 1) PackInit_ComplexType<Kokkos::complex<PetscReal>,1,1>(link); else if (nPetscComplex%1 == 0) PackInit_ComplexType<Kokkos::complex<PetscReal>,1,0>(link);
519 #endif
520   } else {
521     MPI_Aint lb,nbyte;
522     ierr = MPI_Type_get_extent(unit,&lb,&nbyte);CHKERRQ(ierr);
523     if (lb != 0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_SUP,"Datatype with nonzero lower bound %ld\n",(long)lb);
524     if (nbyte % sizeof(int)) { /* If the type size is not multiple of int */
525       if      (nbyte == 4) PackInit_DumbType<char,4,1>(link); else if (nbyte%4 == 0) PackInit_DumbType<char,4,0>(link);
526       else if (nbyte == 2) PackInit_DumbType<char,2,1>(link); else if (nbyte%2 == 0) PackInit_DumbType<char,2,0>(link);
527       else if (nbyte == 1) PackInit_DumbType<char,1,1>(link); else if (nbyte%1 == 0) PackInit_DumbType<char,1,0>(link);
528     } else {
529       nInt = nbyte / sizeof(int);
530       if      (nInt == 8) PackInit_DumbType<int,8,1>(link); else if (nInt%8 == 0) PackInit_DumbType<int,8,0>(link);
531       else if (nInt == 4) PackInit_DumbType<int,4,1>(link); else if (nInt%4 == 0) PackInit_DumbType<int,4,0>(link);
532       else if (nInt == 2) PackInit_DumbType<int,2,1>(link); else if (nInt%2 == 0) PackInit_DumbType<int,2,0>(link);
533       else if (nInt == 1) PackInit_DumbType<int,1,1>(link); else if (nInt%1 == 0) PackInit_DumbType<int,1,0>(link);
534     }
535   }
536 
537 #if defined(KOKKOS_ENABLE_CUDA)
538   if (!sf->use_default_stream) {cudaError_t cerr = cudaStreamCreate(&link->stream);CHKERRCUDA(cerr);}
539   link->sptr         = new DeviceExecutionSpace(link->stream);
540 #elif defined(KOKKOS_ENABLE_HIP)
541   if (!sf->use_default_stream) {hipError_t cerr = hipStreamCreate(&link->stream);CHKERRQ(cerr);}
542   link->sptr         = new DeviceExecutionSpace(link->stream);
543 #endif
544 
545   link->d_SyncDevice = PetscSFLinkSyncDevice_Kokkos;
546   link->d_SyncStream = PetscSFLinkSyncStream_Kokkos;
547   link->Memcpy       = PetscSFLinkMemcpy_Kokkos;
548   link->Destroy      = PetscSFLinkDestroy_Kokkos;
549   link->deviceinited = PETSC_TRUE;
550   PetscFunctionReturn(0);
551 }
552