[UR][L0v2][SYCL] Avoid redundant global timestamp query for profiling tag events - #22810
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againull wants to merge 5 commits into
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[UR][L0v2][SYCL] Avoid redundant global timestamp query for profiling tag events#22810againull wants to merge 5 commits into
againull wants to merge 5 commits into
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… tag events submit_profiling_tag and enqueue_signal_event already record a GPU-written global timestamp via zeCommandListAppendWriteGlobalTimestamp. The additional urDeviceGetGlobalTimestamps call used to capture the submission and start times adds no value, since users only rely on the end timestamp. Change the specification and implementation so that a tag event carries a single timestamp, reported alike for command_submit, command_start and command_end. This drops the call in both the UR L0 v2 adapter and the SYCL RT, removes the now-unused start-timestamp machinery. Tests updated accordingly (the three fields are now equal for tag operations). Assisted-By: Claude
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Jul 30, 2026
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removes the now-unused start-timestamp machinery
Just checking ... we still set the start timestamp for other events, right? For example, events returned from queue::submit.
The follow-up commits keep command_submit <= command_start <= command_end for tag events (immediate queues report a single timestamp for all three; batched queues still record a distinct submission time). The observable semantics thus match the original specification, so the spec wording and ProfilingTag test assertions are restored to their pre-change form. Assisted-By: Claude
…tags The initial version reported command_submit == command_start == command_end for all tag events and dropped the urDeviceGetGlobalTimestamps query. That query is only redundant for immediate queues, where the tag is submitted right away. Reintroduce the query for batched queues (ur_queue_batched_t), where submission is deferred and command_submit meaningfully precedes execution, while keeping immediate queues on the fast path (no query; the GPU-written timestamp is reported for all fields). appendTimestampRecordingExp gains a recordSubmit flag set by the queue. The recorded submission timestamp is also the reference for end-timestamp wrap-around correction. The SYCL RT no longer records a host submission time for tag events, relying on the adapter for command_submit. Assisted-By: Claude
Apply the same optimization to the L0 v1 adapter: in urEnqueueTimestampRecordingExp, query urDeviceGetGlobalTimestamps for command_submit only for batched (non-immediate) queues, where submission is deferred. Immediate queues report the GPU-written timestamp for command_submit as well. The recorded submission timestamp, when present, is the reference for end-timestamp wrap-around correction. Assisted-By: Claude
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Yes, that' correct. |
Following the spec agreement, a tag operation (submit_profiling_tag / enqueue_signal_event) is an empty command, so command_submit, command_start and command_end all report the single GPU-written completion timestamp. This removes the batched-queue special case added earlier (the extra urDeviceGetGlobalTimestamps query for command_submit and the associated wrap-around handling) from both the L0 v1 and v2 adapters. Assisted-By: Claude
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Specification change: #22847
submit_profiling_tagandenqueue_signal_eventalready record a GPU-written global timestamp viazeCommandListAppendWriteGlobalTimestamp. The additionalurDeviceGetGlobalTimestampscall used to capture the submission and start times adds no value, since users only rely on the end timestamp.Change implementation so that a tag event carries a single timestamp, reported alike for
command_submit,command_startandcommand_end.Assisted-By: Claude