On Fri, Feb 27, 2026 at 04:00:22PM +0000, 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.
I don't like this at all. We have CONFIG_LOCK_STAT. That should be improved insted of coming up with one-offs for every single lock that someone deems "special".
