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  1. MariaDB Server
  2. MDEV-27935

Enable performance_schema profiling for trx_rseg_t latch

Details

    Description

      • In 10.6, trx_rseg_t mutex was ported to use latch. As part of this porting profiling of the patch was removed. This patch reenables it given that the said latch continues to occupy the top slots in the contention list

      When I applied the said patch and enabled profiling trx_rseg_latch_key was 2nd hottest instrument from the InnoDB SE perspective.

      wait/synch/cond/threadpool/worker_cond 46351983.3024 167603
      wait/synch/mutex/innodb/log_sys_mutex 8716632.1922 122968738
      wait/synch/cond/mysys/COND_timer 1516437.4227 5397
      wait/synch/cond/threadpool/timer_cond 1515688.2689 3025
      wait/synch/cond/aria/SERVICE_THREAD_CONTROL::COND_control 1501997.0416 50
      wait/synch/rwlock/innodb/trx_rseg_latch_key 342616.7699 98834024

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          causes

          Bug - A problem which impairs or prevents the functions of the product. MDEV-28049 Error on compiling of trx0purge.cc

          • Blocker - Blocks development and/or testing work, production could not run.
          • Closed
          is caused by

          Bug - A problem which impairs or prevents the functions of the product. MDEV-25062 InnoDB read-write workload hits contention arising from rollback segment mutex

          • Major - Major loss of function.
          • Closed

          Activity

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            krunalbauskar Krunal Bauskar added a comment -

            PR submitted: https://github.com/MariaDB/server/pull/2032

            krunalbauskar Krunal Bauskar added a comment - PR submitted: https://github.com/MariaDB/server/pull/2032
            marko Marko Mäkelä added a comment -

            Thank you, Krunal! The patch looks good to me.

            Can you please show the performance impact of this when performance_schema is available but globally disabled at runtime?

            marko Marko Mäkelä added a comment - Thank you, Krunal! The patch looks good to me. Can you please show the performance impact of this when performance_schema is available but globally disabled at runtime?
            marko Marko Mäkelä added a comment -

            I had intentionally removed the PERFORMANCE_SCHEMA instrumentation in MDEV-25062 when replacing the mutexes with rw-locks. I stand corrected that it still is a serious contention point.

            marko Marko Mäkelä added a comment - I had intentionally removed the PERFORMANCE_SCHEMA instrumentation in MDEV-25062 when replacing the mutexes with rw-locks. I stand corrected that it still is a serious contention point.
            krunalbauskar Krunal Bauskar added a comment -

            @Marko,

            Please check the attached graph fro x86. There is no impact due to adding pfs support for the said latch.

            krunalbauskar Krunal Bauskar added a comment - @Marko, Please check the attached graph fro x86. There is no impact due to adding pfs support for the said latch.

            People

              marko Marko Mäkelä
              krunalbauskar Krunal Bauskar
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              Dates

                Created:
                Updated:
                Resolved:

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