[SYCL] Wait before deleting a stream buffer #2646
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againull
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Currently streamed data is printed in a host task. Host task has a corresponding empty task which is a leaf command for a stream buffer. Since stream buffer is not a leaf for a kernel it doesn't block the kernel from being cleaned up after completion. During this cleanup process stream buffer is deleted, as a result scheduler does a blocking enqueue of the empty task. Problem is that this empty task has a blocked status (blocked by host task). This results in exception saying that we try to wait for a blocked command. It is not clear if this use case is invalid or there is a bug in the scheduler. Explicitly waiting for a host task before stream buffer deletion is correct for sure and resolves this problem.
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/summary:run |
s-kanaev
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Oct 16, 2020
| auto Q = detail::createSyclObjFromImpl<queue>( | ||
| cl::sycl::detail::Scheduler::getInstance().getDefaultHostQueue()); | ||
| Q.submit([&](handler &cgh) { | ||
| auto Event = Q.submit([&](handler &cgh) { |
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During this cleanup process stream buffer is deleted, as a result scheduler does a blocking enqueue of the empty task.
As far as I understand the cleanup may happen right after the kernel is executed while the printing host-task isn't executed yet. Is that correct?
Hence, I wonder if it is possible that stream_impl::flush is invoked after kernel's execution?
romanovvlad
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Oct 16, 2020
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I'm not sure it's a bug, let's discuss offline.
kbenzie
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Feb 17, 2025
Refactor KNOWN_FAILURE implementation to avoid repeated logic.
Chenyang-L
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Refactor KNOWN_FAILURE implementation to avoid repeated logic.
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Currently streamed data is printed in a host task. Host task has a corresponding empty task which is a leaf command for a stream buffer. Since stream buffer is not a leaf for a kernel it doesn't block the kernel from being cleaned up after completion. During this cleanup process stream buffer is deleted, as a result scheduler does a blocking enqueue of the empty task. Problem is that this empty task has a blocked status (blocked by host task). This results in exception saying that we try to wait for a blocked command. It is not clear if this use case is invalid or there is a bug in the scheduler.
Explicitly waiting for a host task before stream buffer deletion is correct for sure and resolves this problem.