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-17242 Lustre <p>Some parts of Lustre debugging have been superseded by newer kernel features (such as CFS_CHECK_STACK) and should be removed.</p> <p>Certain subsystems stack custom macros on-top of Lustre's already custom debugging. Those should be simplified if possible.</p> <p>Other subsystems use low-level debugging functions such as libcfs_debug_msg. These should use the higher level macros. That way, the underlying debugging implementation can more easily be swapped out.</p> LU-17242

Clean up and Improve Lustre Debugging

Improvement Minor Open Unresolved Tim Day Tim Day Mon, 30 Oct 2023 02:58:20 +0000 Sun, 4 Feb 2024 08:31:32 +0000 0 6 <p>"Timothy Day &lt;timday@amazon.com&gt;" uploaded a new patch: <a href="https://review.whamcloud.com/c/fs/lustre-release/+/52883" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/c/fs/lustre-release/+/52883</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-17242" title="Clean up and Improve Lustre Debugging" class="issue-link" data-issue-key="LU-17242">LU-17242</a> debug: remove CFS_CHECK_STACK<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: 1<br/> Commit: 0d01390b5c371e76b315d38ff5213078057317da</p> <p>"Timothy Day &lt;timday@amazon.com&gt;" uploaded a new patch: <a href="https://review.whamcloud.com/c/fs/lustre-release/+/52897" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/c/fs/lustre-release/+/52897</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-17242" title="Clean up and Improve Lustre Debugging" class="issue-link" data-issue-key="LU-17242">LU-17242</a> ptlrpc: refactor DEBUG_REQ to use CDEBUG<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: 1<br/> Commit: 16368c2dbe8d3b095f43701237eed490e5a93c6d</p> <p>"Timothy Day &lt;timday@amazon.com&gt;" uploaded a new patch: <a href="https://review.whamcloud.com/c/fs/lustre-release/+/52946" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/c/fs/lustre-release/+/52946</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-17242" title="Clean up and Improve Lustre Debugging" class="issue-link" data-issue-key="LU-17242">LU-17242</a> debug: CDEBUG performance testing<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: 1<br/> Commit: 00918c7a9402599e1ffd56b613ddf5ec67cc421d</p> <p>What would be incredibly useful for debugging is if there was some way to get some additional information printed with the kernel stack trace, such as which MDT/OST target a thread was working on, maybe if it is holding any DLM locks, etc.</p> <p>One option would be to have some reserved fields in the thread-local storage or <tt>lu_env</tt> that holds pointers to the OBD device (or just the name), pointers to the DLM lock(s), etc. and then the <tt>LASSERT()</tt> or <tt>lbug_with_loc()</tt> looks up this information and prints it before triggering <tt>panic()</tt> or going to sleep. The fields in the thread-local area would need to be "well defined" so that they do not depend on the thread context, and they should always contain valid pointers (e.g. set when a DLM lock is acquired, NULL when the lock is released, or NULL when a server thread stops processing an RPC or when a client thread exits OSC/LOV/MDC/LMV).</p> <p>It would also be useful on the server to print in the stack trace when the thread has a journal transaction open, and potentially this could also be submitted to the upstream kernel to print <tt>current-&gt;journal_info</tt> as part of the stack trace? For now, this could at least be printed by <tt>libcfs_call_trace()</tt>.</p> <p>It might be too messy to set/clear a field whenever a mutex/semaphore is held, </p> <p>Thoughts?</p> <p>Seems useful. I think we could register a custom panic handler. I see upstream drivers (like drivers/net/ipa/ipa_smp2p.c) doing something like that. We could avoid extending custom Lustre debugging and it should work on every panic. Adding `current-&gt;journal_info` to the handler would be easy. Getting the Lustre specific info might be tougher, but I saw some ideas upstream we could probably copy. The `ipa` just embedded the `notifier_block` in a larger struct and used `container_of` to get everything else.</p> <p>"Oleg Drokin &lt;green@whamcloud.com&gt;" merged in patch <a href="https://review.whamcloud.com/c/fs/lustre-release/+/52883/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/c/fs/lustre-release/+/52883/</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-17242" title="Clean up and Improve Lustre Debugging" class="issue-link" data-issue-key="LU-17242">LU-17242</a> debug: remove CFS_CHECK_STACK<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: <br/> Commit: edb968d04f3a3c8054c12daee1ba557f855055ce</p> <p>"Timothy Day &lt;timday@amazon.com&gt;" uploaded a new patch: <a href="https://review.whamcloud.com/c/fs/lustre-release/+/53625" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/c/fs/lustre-release/+/53625</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-17242" title="Clean up and Improve Lustre Debugging" class="issue-link" data-issue-key="LU-17242">LU-17242</a> debug: use dump_stack() where possible<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: 1<br/> Commit: 1debf098028fec7c27310d0985934eeee4e0a67a</p> <p>"Oleg Drokin &lt;green@whamcloud.com&gt;" merged in patch <a href="https://review.whamcloud.com/c/fs/lustre-release/+/53625/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/c/fs/lustre-release/+/53625/</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-17242" title="Clean up and Improve Lustre Debugging" class="issue-link" data-issue-key="LU-17242">LU-17242</a> debug: use dump_stack() where possible<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: <br/> Commit: ecac0c175d934fd5624c9ad8db8f45dbc33fb56c</p> Related LU-17075 LU-16625 Development Rank 1|i03zyf: Rank (Obsolete) 9223372036854775807 Severity