From: Peter Zijlstra <peterz@infradead.org>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: mingo@redhat.com, will@kernel.org, boqun@kernel.org,
longman@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org,
mark.rutland@arm.com, mathieu.desnoyers@efficios.com,
david.laight.linux@gmail.com, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 0/3] disable optimistic spinning for ftrace_lock
Date: Wed, 11 Mar 2026 12:54:26 +0100 [thread overview]
Message-ID: <20260311115426.GN606826@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20260311115250.78488-1-laoar.shao@gmail.com>
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.
next prev parent reply other threads:[~2026-03-11 11:54 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-11 11:52 [RFC PATCH v2 0/3] disable optimistic spinning for ftrace_lock Yafang Shao
2026-03-11 11:52 ` [RFC PATCH v2 1/3] locking/mutex: Add slow path variants for lock/unlock Yafang Shao
2026-03-11 11:52 ` [RFC PATCH v2 2/3] locking/rtmutex: " Yafang Shao
2026-03-11 11:52 ` [RFC PATCH v2 3/3] ftrace: Disable optimistic spinning for ftrace_lock Yafang Shao
2026-03-11 11:54 ` Peter Zijlstra [this message]
2026-03-11 11:55 ` [RFC PATCH v2 0/3] disable " Yafang Shao
2026-03-11 12:53 ` David Laight
2026-03-11 13:40 ` Yafang Shao
2026-03-11 17:07 ` Steven Rostedt
2026-03-11 17:39 ` Steven Rostedt
2026-03-11 19:05 ` David Laight
2026-03-12 8:06 ` Masami Hiramatsu
2026-03-12 8:57 ` Yafang Shao
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