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[SYCL][PI][L0] Force reset of memcpy command-list. #4001

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Jun 29, 2021
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[SYCL][PI][L0] Force reset of memcpy command-list. #4001

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[SYCL][PI][L0] Force reset of memcpy command-list.
kbsmith-intel Jun 25, 2021
2d7ee9b
Fixes clang-format problem in previous commit.
kbsmith-intel Jun 25, 2021
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27 changes: 20 additions & 7 deletions sycl/plugins/level_zero/pi_level_zero.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -185,10 +185,9 @@ template <> ze_result_t zeHostSynchronize(ze_event_handle_t Handle) {
template <> ze_result_t zeHostSynchronize(ze_command_queue_handle_t Handle) {
return zeHostSynchronizeImpl(zeCommandQueueSynchronize, Handle);
}
// template <>
// ze_result_t zeHostSynchronize(ze_fence_handle_t Handle) {
// return zeHostSynchronizeImpl(zeFenceHostSynchronize, Handle);
// }
template <> ze_result_t zeHostSynchronize(ze_fence_handle_t Handle) {
return zeHostSynchronizeImpl(zeFenceHostSynchronize, Handle);
}

template <typename T, typename Assign>
pi_result getInfoImpl(size_t param_value_size, void *param_value,
Expand Down Expand Up @@ -4231,11 +4230,25 @@ static pi_result cleanupAfterEvent(pi_event Event) {
}

// It is possible that the fence was already noted as signalled and
// reset. In that case the InUse flag will be false, and there is
// no need to query the fence's status or try to reset it.
// reset. In that case the InUse flag will be false, and
// we shouldn't query it, synchronize on it, or try to reset it.
if (it->second.InUse) {
// Workaround for VM_BIND mode.
// Make sure that the command-list doing memcpy is reset before
// non-USM host memory potentially involved in the memcpy is freed.
//
// NOTE: it is valid to wait for the fence here as long as we aren't
// doing batching on the involved command-list. Today memcpy goes by
// itself in a command list.
//
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Not sure if this NOTE: portion of the comment is accurate. I think batching can still be done on memcpy, but if we do batching on memcpy, then first memcpy event in the command list that finishes will force a fence synchronization for the whole command list. I also think it would be OK to batch, and just force a memcpy to be the last command put into a batch.

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I also think it would be OK to batch, and just force a memcpy to be the last command put into a batch.

That's what I called no batching of memory copies, i.e. where same command-list would contain multiple memory copies. Yes, memcpy must be the last command in the batch, i.e. close the batch, in order for this fence wait logic here to be correct.

// TODO: this will unnecessarily(?) wait for non-USM memory buffers
// too, so we might need to add a new command type to differentiate.
//
ze_result_t ZeResult =
ZE_CALL_NOCHECK(zeFenceQueryStatus, (it->second.ZeFence));
(Event->CommandType == PI_COMMAND_TYPE_MEM_BUFFER_COPY)
? ZE_CALL_NOCHECK(zeHostSynchronize, (it->second.ZeFence))
: ZE_CALL_NOCHECK(zeFenceQueryStatus, (it->second.ZeFence));

if (ZeResult == ZE_RESULT_SUCCESS) {
Queue->resetCommandListFenceEntry(*it, true);
Event->ZeCommandList = nullptr;
Expand Down