From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Dmitry Ilvokhin <d@ilvokhin.com>, Dennis Zhou <dennis@kernel.org>,
Tejun Heo <tj@kernel.org>, Christoph Lameter <cl@gentwo.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Boqun Feng <boqun@kernel.org>, Waiman Long <longman@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org, kernel-team@meta.com
Subject: Re: [PATCH RFC 3/3] locking: Wire up contended_release tracepoint
Date: Thu, 5 Mar 2026 18:42:23 +0100 [thread overview]
Message-ID: <20260305174223.GA1442992@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20260305105924.7069eb23@gandalf.local.home>
On Thu, Mar 05, 2026 at 10:59:24AM -0500, Steven Rostedt wrote:
> On Wed, 4 Mar 2026 16:56:17 +0000
> Dmitry Ilvokhin <d@ilvokhin.com> wrote:
>
> > @@ -204,6 +206,8 @@ static inline void rwbase_write_unlock(struct rwbase_rt *rwb)
> > unsigned long flags;
> >
> > raw_spin_lock_irqsave(&rtm->wait_lock, flags);
> > + if (rt_mutex_has_waiters(rtm))
> > + trace_contended_release(rwb);
>
> Hmm, if statements should never be used just for tracepoints without a
> static branch. The above should be:
>
> if (trace_contended_release_enabled() && rt_mutex_has_waiters(rtm))
> trace_contended_release(rwb);
>
I still wish you would accept:
if (trace_foo_enabled() && foo)
__do_trace_foo();
The compilers can't optimize the static branches and thus you'll get it
twice for no reason.
I really wish they would just accept __pure, but alas.
next prev parent reply other threads:[~2026-03-05 17:42 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-04 16:56 [PATCH RFC 0/3] locking: contended_release tracepoint instrumentation Dmitry Ilvokhin
2026-03-04 16:56 ` [PATCH RFC 1/3] locking: Add contended_release tracepoint Dmitry Ilvokhin
2026-03-04 22:55 ` Masami Hiramatsu
2026-03-10 15:58 ` Dmitry Ilvokhin
2026-03-04 16:56 ` [PATCH RFC 2/3] locking/percpu-rwsem: Extract __percpu_up_read_slowpath() Dmitry Ilvokhin
2026-03-04 22:02 ` Peter Zijlstra
2026-03-05 15:47 ` Steven Rostedt
2026-03-05 16:05 ` Peter Zijlstra
2026-03-10 15:26 ` Dmitry Ilvokhin
2026-03-04 16:56 ` [PATCH RFC 3/3] locking: Wire up contended_release tracepoint Dmitry Ilvokhin
2026-03-05 15:59 ` Steven Rostedt
2026-03-05 17:42 ` Peter Zijlstra [this message]
2026-03-05 18:06 ` Steven Rostedt
2026-03-10 15:12 ` Dmitry Ilvokhin
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