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Improved visibility into > its behavior is therefore important for diagnosing performance > issues in memory-intensive workloads. > > On some production workloads at Meta, we have observed noticeable > zone lock contention. Deeper analysis of lock holders and waiters > is currently difficult with existing instrumentation. > > While generic lock contention_begin/contention_end tracepoints > cover the slow path, they do not provide sufficient visibility > into lock hold times. In particular, the lack of a release-side > event makes it difficult to identify long lock holders and > correlate them with waiters. As a result, distinguishing between > short bursts of contention and pathological long hold times > requires additional instrumentation. > > This patch series adds dedicated tracepoint instrumentation to > zone lock, following the existing mmap_lock tracing model. > > The goal is to enable detailed holder/waiter analysis and lock > hold time measurements without affecting the fast path when > tracing is disabled. > > The series is structured as follows: > > 1. Introduce zone lock wrappers. > 2. Mechanically convert zone lock users to the wrappers. > 3. Convert compaction to use the wrappers (requires minor > restructuring of compact_lock_irqsave()). > 4. Add zone lock tracepoints. I think you can improve the flow of this series if reorder as follows: 1. Introduce zone lock wrappers 4. Add zone lock tracepoints 2. Mechanically convert zone lock users to the wrappers 3. Convert compaction to use the wrappers... and possibly squash 1 & 4 (though that might be too big of a patch). It's better to introduce the wrappers and their tracepoints together before the reviewer (i.e. me) forgets what was added in patch 1 by the time they get to patch 4. Thanks, Ben