https://jira.whamcloud.com This file is an XML representation of an issue en-us 9.4.14 940014 05-12-2023 https://jira.whamcloud.com/browse/LU-11347 Lustre <p>For SSD optimization, disable pagecache for IO when:</p> <ul> <li>non-rotational storage is used</li> <li>when both read and write caches are disabled</li> </ul> LU-11347

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

Improvement Major Resolved Fixed Alex Zhuravlev Joseph Gmitter perf_optimization Thu, 6 Sep 2018 04:08:56 +0000 Mon, 15 Jun 2020 19:44:52 +0000 Sat, 13 Oct 2018 04:58:00 +0000 Lustre 2.12.0 0 10 <p>test only patch is at <a href="https://review.whamcloud.com/#/c/32875/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/#/c/32875/</a></p> <p> </p> <p>Attached flame graph ( <span class="nobr"><a href="https://jira.whamcloud.com/secure/attachment/31097/31097_ost_io.svg" title="ost_io.svg attached to LU-11347">ost_io.svg^{<img class="rendericon" src="https://jira.whamcloud.com/images/icons/link_attachment_7.gif" height="7" width="7" align="absmiddle" alt="" border="0"/>}</a></span> ) shows <tt>find_or_create_page()</tt> using 4.25% of CPU under heavy random read workload (using fake IO to avoid storage overhead)..</p> <p>Oleg Drokin (green@whamcloud.com) merged in patch <a href="https://review.whamcloud.com/32875/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/32875/</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-11347" title="Do not use pagecache for SSD I/O when read/write cache are disabled" class="issue-link" data-issue-key="LU-11347"><del>LU-11347</del></a> osd: do not use pagecache for I/O<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: <br/> Commit: 72372486a5e96dd2078e01a697025da41bbf03c2</p> <p>Landed for 2.12</p> <p>Alex, Andreas:<br/> According to <a href="https://jira.whamcloud.com/browse/LU-9252" title="osd: Cannot really disable cache on OSS" class="issue-link" data-issue-key="LU-9252"><del>LU-9252</del></a> this patch is needed to disable osd cache.</p> <p>Would it be possible to have it ported to b2_10?</p> <p>It would be possible to do this but we have no plans to do this at this time</p> <p>I think it would be beneficial in some cases. <br/> 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)</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java"> + 34.99% 0.35% 7 ll_ost_io01_034 [kernel.vmlinux] [k] find_or_create_page </pre> </div></div> <p>I have already backported the patch - if it's possible to submit it for autotesting it would be great</p> <p> </p> Related LU-5375 LU-13680 LU-12179 LU-9252 LU-11164 LU-12071 Development Rank 1|i001xj: Rank (Obsolete) 9223372036854775807