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-9252 Lustre <p> When deactivating caching on an OSS through the osd proc files: <tt>read_cache_enable</tt> and <tt>writethrough_cache_enable</tt>, it only simulates Lustre's behaviour without cache.</p> <p>It would be interesting though, for Lustre's OSSes to be able to allocate their memory outside of the pagecache for it seems to be a performance issues when using SSD disks: it creates a CPU overload and 65% of CPU ressources are spent to allocate/free memory from the pagecache.</p> LU-9252

osd: Cannot really disable cache on OSS

Improvement Minor Resolved Duplicate Peter Jones CEA performance Fri, 24 Mar 2017 09:21:18 +0000 Wed, 5 Aug 2020 13:50:25 +0000 Thu, 31 Jan 2019 23:47:49 +0000 0 9 <p>To clarify your concern, the issue is that even with read/write cache disabled the OSS is still adding the pages to the mapping for the inode and then dropping it after the read/write is complete.</p> <p>It should be possible to change this caching behaviour for osd-ldiskfs to preallocate IO buffers per thread, in a manner similar to what Lustre 1.8 did, but I don't think it would be possible to do this for osd-zfs.</p> <p>This was fixed via <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> to preallocate IO buffers in this case.</p> Related LU-11347 Development Rank 1|hzz87j: Rank (Obsolete) 9223372036854775807 Severity