copr: improve observability of total suspend time#19178
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ti-chi-bot[bot] merged 2 commits intotikv:masterfrom Dec 10, 2025
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copr: improve observability of total suspend time#19178ti-chi-bot[bot] merged 2 commits intotikv:masterfrom
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What’s changed? - Include coprocessor suspend time in the existing copr wait time metric - Add metrics for semaphore waiting time and the number of copr tasks waiting on the semaphore. Background: - `total_suspend_time` measures how long a coprocessor task is not actually being processed. This can be prolonged for several reasons, including YATP scheduling wait and waiting for the concurrency limiter semaphore. Previously, `total_suspend_time` was only visible in TiKV’s slow query logs. - Semaphore waiting is one of the main contributors to long suspend times. The concurrency limiter exists to prioritize completing a limited number of heavy tasks rather than spreading work thin across too many tasks, which could cause all of them to make slow progress. In this mechanism, when a copr task runs for more than 5 ms, it must acquire a semaphore permit before continuing. The total number of permits defaults to the number of CPU cores. Signed-off-by: Bisheng Huang <hbisheng@gmail.com>
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close tikv#19179 Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>
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close #19179 Changes: - Include coprocessor suspend time in the existing copr wait time metric - Add panels for semaphore waiting time and the number of copr tasks waiting on the semaphore. Background: - `total_suspend_time` measures how long a coprocessor task is not actually being processed. This can be prolonged for several reasons, including YATP scheduling wait and waiting for the concurrency limiter semaphore. Previously, `total_suspend_time` was only visible in TiKV’s slow query logs. - Semaphore waiting is one of the main contributors to long suspend times. The concurrency limiter exists to prioritize completing a limited number of heavy tasks rather than spreading work thin across too many tasks. In this mechanism, when a copr task runs for more than 5ms, it must acquire a semaphore permit before continuing. The total number of permits defaults to the number of CPU cores. Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io> Signed-off-by: Bisheng Huang <hbisheng@gmail.com> Co-authored-by: Bisheng Huang <hbisheng@gmail.com>
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What is changed and how it works?
Issue Number: Close #19179
What's Changed:
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