On Fri, Feb 20, 2026 at 01:09:59PM -0600, Cheatham, Benjamin wrote: > On 2/11/2026 9:22 AM, Dmitry Ilvokhin wrote: > > Zone lock contention can significantly impact allocation and > > reclaim latency, as it is a central synchronization point in > > the page allocator and reclaim paths. 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.
I don't think this suggestion will make anything better. This just seems like a different taste. If I make a suggestion, I would request to squash (1) and (2) i.e. patch containing wrappers and their use together but that is just my taste and would be a nit. The series ordering is good as is.
