On Wed, Mar 11, 2026 at 07:52:47PM +0800, Yafang Shao wrote: > Recently, we resolved a latency spike issue caused by concurrently running > bpftrace processes. The root cause was high contention on the ftrace_lock > due to optimistic spinning. We can optimize this by disabling optimistic > spinning for ftrace_lock. > > While semaphores may present similar challenges, I'm not currently aware of > specific instances that exhibit this exact issue. Should we encounter > problematic semaphores in production workloads, we can address them at that > time. > > PATCH #1: introduce slow_mutex_[un]lock to disable optimistic spinning > PATCH #2: add variant for rtmutex > PATCH #3: disable optimistic spinning for ftrace_lock >
So I really utterly hate this.
