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  1. Lustre
  2. LU-11347

Do not use pagecache for SSD I/O when read/write cache are disabled

Details

    • 9223372036854775807

    Description

      For SSD optimization, disable pagecache for IO when:

      • non-rotational storage is used
      • when both read and write caches are disabled

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          is related to

          Bug - A problem which impairs or prevents the functions of the product. LU-5375 Failure on test suite sanity test_151 test_156: roc_hit is not safe to use

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. LU-13680 large allocations in osd_bufs_get() failing

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Improvement - An improvement or enhancement to an existing feature or task. LU-12179 allocate continuous pages when disabled page caches

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Improvement - An improvement or enhancement to an existing feature or task. LU-9252 osd: Cannot really disable cache on OSS

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Improvement - An improvement or enhancement to an existing feature or task. LU-11164 lvbo_*() methods to reuse env

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Improvement - An improvement or enhancement to an existing feature or task. LU-12071 bypass pagecache for large files

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Activity

            [LU-11347] Do not use pagecache for SSD I/O when read/write cache are disabled
            lflis Lukasz Flis added a comment -

            I think it would be beneficial in some cases.
            In 2.10.7 and mixed workload cluster - profiling of ost_io threads shows that we spend 35% of the thread time in find_or_create_page and kswapd0 being hyperactive (swap is off)

            +   34.99%     0.35%             7  ll_ost_io01_034  [kernel.vmlinux]  [k] find_or_create_page

            I have already backported the patch - if it's possible to submit it for autotesting it would be great

             

            lflis Lukasz Flis added a comment - I think it would be beneficial in some cases. In 2.10.7 and mixed workload cluster - profiling of ost_io threads shows that we spend 35% of the thread time in find_or_create_page and kswapd0 being hyperactive (swap is off) + 34.99% 0.35% 7 ll_ost_io01_034 [kernel.vmlinux] [k] find_or_create_page I have already backported the patch - if it's possible to submit it for autotesting it would be great  
            pjones Peter Jones added a comment -

            It would be possible to do this but we have no plans to do this at this time

            pjones Peter Jones added a comment - It would be possible to do this but we have no plans to do this at this time
            lflis Lukasz Flis added a comment -

            Alex, Andreas:
            According to LU-9252 this patch is needed to disable osd cache.

            Would it be possible to have it ported to b2_10?

            lflis Lukasz Flis added a comment - Alex, Andreas: According to LU-9252 this patch is needed to disable osd cache. Would it be possible to have it ported to b2_10?
            pjones Peter Jones added a comment -

            Landed for 2.12

            pjones Peter Jones added a comment - Landed for 2.12
            gerrit Gerrit Updater added a comment -

            Oleg Drokin (green@whamcloud.com) merged in patch https://review.whamcloud.com/32875/
            Subject: LU-11347 osd: do not use pagecache for I/O
            Project: fs/lustre-release
            Branch: master
            Current Patch Set:
            Commit: 72372486a5e96dd2078e01a697025da41bbf03c2

            gerrit Gerrit Updater added a comment - Oleg Drokin (green@whamcloud.com) merged in patch https://review.whamcloud.com/32875/ Subject: LU-11347 osd: do not use pagecache for I/O Project: fs/lustre-release Branch: master Current Patch Set: Commit: 72372486a5e96dd2078e01a697025da41bbf03c2
            adilger Andreas Dilger added a comment - - edited

            Attached flame graph ( ost_io.svg ) shows find_or_create_page() using 4.25% of CPU under heavy random read workload (using fake IO to avoid storage overhead)..

            adilger Andreas Dilger added a comment - - edited Attached flame graph ( ost_io.svg ) shows find_or_create_page() using 4.25% of CPU under heavy random read workload (using fake IO to avoid storage overhead)..
            jgmitter Joseph Gmitter (Inactive) added a comment -

            test only patch is at https://review.whamcloud.com/#/c/32875/

             

            jgmitter Joseph Gmitter (Inactive) added a comment - test only patch is at https://review.whamcloud.com/#/c/32875/  

            People

              bzzz Alex Zhuravlev
              jgmitter Joseph Gmitter (Inactive)
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              Dates

                Created:
                Updated:
                Resolved: