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  1. MariaDB Server
  2. MDEV-24854

Change innodb_flush_method=O_DIRECT by default

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    Description

      We have innodb_use_native_aio=ON by default since the introduction of that parameter in MariaDB 5.5. However, to really benefit from the setting, the files should be opened in O_DIRECT mode, to bypass the file system cache. In this way, the reads and writes can be submitted with DMA, using the InnoDB buffer pool directly, and no processor cycles need to be used for copying data.

      The setting O_DIRECT should be equivalent to the old default innodb_flush_method=fsync in other aspects. Only the file system cache will be bypassed.

      Note: innodb_flush_method=O_DIRECT in combination with a tiny innodb_buffer_pool_size may cause a significant performance regression, because we will no longer be able to take advantage of the file system cache of the operating system kernel. The InnoDB buffer pool will completely replace it. Affected users should configure innodb_flush_method=fsync.

      This change will not affect Microsoft Windows. The default there is innodb_flush_method=unbuffered, which is roughly equivalent to O_DIRECT.

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          causes

          Bug - A problem which impairs or prevents the functions of the product. MDEV-33095 innodb_flush_method=O_DIRECT creates excessive errors on Solaris

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-26040 os_file_set_size() may not work on O_DIRECT files

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-27772 Performance regression with default configuration in 10.6

          • Major - Major loss of function.
          • Open

          Bug - A problem which impairs or prevents the functions of the product. MDEV-28766 MDEV-28111 breaks innodb_flush_log_at_trx_commit=2

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-28909 Write performance not scale to NVMe SSD

          • Major - Major loss of function.
          • Stalled

          Task - A task that needs to be done. MDEV-30136 Map innodb_flush_method to new settable Booleans innodb_{log,data}_file_{buffering,write_through}

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

          Bug - A problem which impairs or prevents the functions of the product. MDEV-30986 Slow full index scan in 10.6 vs 10.5 for the (slow) I/O-bound case

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-32067 InnoDB linear read ahead had better be logical

          • Major - Major loss of function.
          • Open

          Task - A task that needs to be done. MDEV-32357 Make innodb_flush_method dynamic

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-33379 innodb_log_file_buffering=OFF causes corruption on bcachefs

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Task - A task that needs to be done. MDEV-16526 Overhaul the InnoDB page flushing

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-23855 InnoDB log checkpointing causes regression for write-heavy OLTP

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-27900 aio returning partial reads/writes looks like InnoDB: Database page corruption on btrfs with io_uring

          • Major - Major loss of function.
          • Closed

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              marko Marko Mäkelä
              marko Marko Mäkelä
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