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rocr: Avoid polling for SDMA signals

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When all 64-bits of the signal value are 0, we can skip polling for that
signal.
We need to keep signals as 64-bit numbers as part of the spec. But most
users of ROCr do will never set the signal value to more than 32-bits.
When the dependent-signals are less than 32-bits, avoid adding extra
SDMA poll packet as this adds latency to the SDMA copies.

Change-Id: I37dca65fe3f060dc7164f49b98cb1985023663c4


[ROCm/ROCR-Runtime commit: 0544c2336b]
This commit is contained in:
David Yat Sin
2024-11-22 01:16:17 +00:00
parent 2a492e6f04
commit b7208786a2
1 changed files with 34 additions and 16 deletions
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projects/rocr-runtime/runtime/hsa-runtime/core/runtime/amd_blit_sdma.cpp
+34 -16
View File
@@ -278,10 +278,23 @@ hsa_status_t BlitSdma<RingIndexTy, HwIndexMonotonic, SizeToCountOffset, useGCR>:
const void* cmd, size_t cmd_size, uint64_t size, const std::vector<core::Signal*>& dep_signals,
core::Signal& out_signal, std::vector<core::Signal*>& gang_signals) {
// The signal is 64 bit value, and poll checks for 32 bit value. So we
// need to use two poll operations per dependent signal.
const uint32_t num_poll_command =
static_cast<uint32_t>(2 * dep_signals.size());
uint32_t num_poll_command = 0;
// Cached copy of dep_signals[i]->LoadRelaxed
uint64_t dep_signals_value[dep_signals.size()];
for (size_t i = 0; i < dep_signals.size(); ++i) {
// The signal is 64 bit value, and poll checks for 32 bit value.
// If the signal is already 0, then we do not need to poll.
// If the upper 32-bits of the signal is 0, then we only need to poll the
// lower 32-bits
dep_signals_value[i] = dep_signals[i]->LoadRelaxed();
if (dep_signals_value[i]) {
num_poll_command++;
if (dep_signals_value[i] >> 32)
num_poll_command++;
}
}
const uint32_t total_poll_command_size =
(num_poll_command * poll_command_size_);
@@ -357,18 +370,23 @@ hsa_status_t BlitSdma<RingIndexTy, HwIndexMonotonic, SizeToCountOffset, useGCR>:
uint32_t wrapped_index = WrapIntoRing(curr_index);
for (size_t i = 0; i < dep_signals.size(); ++i) {
uint32_t* signal_addr =
reinterpret_cast<uint32_t*>(dep_signals[i]->ValueLocation());
// Wait for the higher 64 bit to 0.
BuildPollCommand(command_addr, &signal_addr[1], 0);
command_addr += poll_command_size_;
bytes_written_[wrapped_index] = prior_bytes;
wrapped_index += poll_command_size_;
// Then wait for the lower 64 bit to 0.
BuildPollCommand(command_addr, &signal_addr[0], 0);
command_addr += poll_command_size_;
bytes_written_[wrapped_index] = prior_bytes;
wrapped_index += poll_command_size_;
if (dep_signals_value[i]) {
uint32_t* signal_addr =
reinterpret_cast<uint32_t*>(dep_signals[i]->ValueLocation());
if (dep_signals_value[i] >> 32) {
// Wait for the higher 32 bits to 0.
BuildPollCommand(command_addr, &signal_addr[1], 0);
command_addr += poll_command_size_;
bytes_written_[wrapped_index] = prior_bytes;
wrapped_index += poll_command_size_;
}
// Then wait for the lower 32 bits to 0.
BuildPollCommand(command_addr, &signal_addr[0], 0);
command_addr += poll_command_size_;
bytes_written_[wrapped_index] = prior_bytes;
wrapped_index += poll_command_size_;
}
}
if (profiling_enabled && (gang_leader_ || gang_signals.empty())) {