Whamcloud Community JIRA https://jira.whamcloud.com This file is an XML representation of an issue en-us 9.4.14 940014 05-12-2023 [LU-14016] libcfs: use atomic64_t for libcfs_kmemory https://jira.whamcloud.com/browse/LU-14016 Lustre <p>If LNet uses more than ~2.14 GB of memory, then lnet_memused will display negative numbers.</p> LU-14016 libcfs: use atomic64_t for libcfs_kmemory Bug Minor Resolved Fixed Amir Shehata Amir Shehata Wed, 7 Oct 2020 18:23:43 +0000 Thu, 29 Oct 2020 11:55:53 +0000 Thu, 29 Oct 2020 11:55:53 +0000 Lustre 2.14.0 0 4 <p>Amir Shehata (ashehata@whamcloud.com) uploaded a new patch: <a href="https://review.whamcloud.com/40168" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/40168</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-14016" title="libcfs: use atomic64_t for libcfs_kmemory" class="issue-link" data-issue-key="LU-14016"><del>LU-14016</del></a> libcfs: use atomic64_t for libcfs_kmemory<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: 1<br/> Commit: 138267a313d645d3bab22f3e0045c586af85b813</p> <p>It would probably be good (in a follow-on patch) to change <tt>libcfs_kmem</tt> (and <tt>obd_memory</tt>) to be <tt>struct percpu_counter</tt> instead of <tt>atomic64_t</tt> to avoid the overhead of atomic updates for every allocation, since we don't really depend on the <b>current</b> value of this variable for anything, only the eventual global consistency.</p> <p>That would mostly be a matter of changing <tt>libcfs_kmem_read()</tt> to use <tt>percpu_counter_sum()</tt> (it is only used at module startup/shutdown so accuracy is more important than performance), <tt>libcfs_kmem_inc/dec()</tt> to use <tt>percpu_counter_add_batch()</tt> (with a batch=1M or so, since we don't need frequent updates, only enough for <tt>fcb-&gt;count</tt> to be updated for <tt>lnet_memused</tt> to be relatively accurate), and adding <tt>percpu_counter_init(&amp;libcfs_kmem)</tt> at the start of <tt>libcfs_init()</tt> and <tt>percpu_counter_destroy(&amp;libcfs_kmem)</tt> after its last usage in <tt>libcfs_exit()</tt>.</p> <p>Oleg Drokin (green@whamcloud.com) merged in patch <a href="https://review.whamcloud.com/40168/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/40168/</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-14016" title="libcfs: use atomic64_t for libcfs_kmemory" class="issue-link" data-issue-key="LU-14016"><del>LU-14016</del></a> libcfs: use atomic64_t for libcfs_kmem<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: <br/> Commit: 9397f8cf866ad363bc3908b248f41adfa5bd8f1c</p> <p>Landed for 2.14</p> Related Development Rank 1|i01brz: Rank (Obsolete) 9223372036854775807 Severity