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-15058 Lustre <p>When memory allocation grow top large the method of allocation moves from kmalloc to vmalloc. Using vmalloc() uses global locking which greatly degrades performance. For ORNL we ended up preventing users form creating files stripped greater than 512. This problem impact very large RPC and other components of Lustre. The solution is to use the generic_radix work present in newer kernel developed for this very issue.</p> Any client or server running Lustre. LU-15058

replace critical vmalloc allocations with genradix

Improvement Major Open Unresolved James A Simmons James A Simmons Mon, 4 Oct 2021 18:21:26 +0000 Mon, 14 Nov 2022 08:24:50 +0000 Lustre 2.15.0 0 4 <p>Can you provide more references on how genradix trees are used to solve this memory allocation problem?</p> <p>The description in the kernel docs doesn't suggest they're for this sort of problem:<br/> <a href="https://www.kernel.org/doc/html/latest/core-api/generic-radix-tree.html" class="external-link" target="_blank" rel="nofollow noopener">"</a>Generic radix trees/sparse arrays</p> <p>Very simple and minimalistic, supporting arbitrary size entries up to PAGE_SIZE."[<br/> <a href="https://www.kernel.org/doc/html/latest/core-api/generic-radix-tree.html" class="external-link" target="_blank" rel="nofollow noopener">https://www.kernel.org/doc/html/latest/core-api/generic-radix-tree.html</a>]</p> <p>See Linux commit ba20ba2e3743bac786dff777954c11930256075e. Reading the commit you will see generic radix trees is a direct replacement of flex_array. The link - <a href="https://www.kernel.org/doc/html/v4.14/core-api/flexible-arrays.html." class="external-link" target="_blank" rel="nofollow noopener">https://www.kernel.org/doc/html/v4.14/core-api/flexible-arrays.html</a> states the purpose of flexible arrays was to handle the described issue. Currently the only user is procfs. flexible arrays never had that many users.</p> <p>Ah, OK - thanks.</p> <p>"James Simmons &lt;jsimmons@infradead.org&gt;" uploaded a new patch: <a href="https://review.whamcloud.com/c/fs/lustre-release/+/48883" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/c/fs/lustre-release/+/48883</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-15058" title="replace critical vmalloc allocations with genradix" class="issue-link" data-issue-key="LU-15058">LU-15058</a> osc: replace large RPC allocations with genradix<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: 1<br/> Commit: da4bf845b7e9a5de9ef44e874d434854994b41f7</p> <p>"Oleg Drokin &lt;green@whamcloud.com&gt;" merged in patch <a href="https://review.whamcloud.com/c/fs/lustre-release/+/45890/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/c/fs/lustre-release/+/45890/</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-15058" title="replace critical vmalloc allocations with genradix" class="issue-link" data-issue-key="LU-15058">LU-15058</a> libcfs: introduce genradix support<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: <br/> Commit: 841843f44cd16e2bfb9b31195f7398cff02f9088</p> Duplicate LU-15606 Related LU-14469 LU-13212 Development Rank 1|i0267b: Rank (Obsolete) 9223372036854775807