From: "Paul E. McKenney" <paulmck@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
rcu@vger.kernel.org, Frederic Weisbecker <fweisbec@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [RCU] rcu_tasks_trace_qs(): trc_reader_special.b.need_qs value incorrect likely()?
Date: Tue, 5 Dec 2023 14:01:05 -0800 [thread overview]
Message-ID: <770fa784-d9cd-456c-b651-221c485a65ea@paulmck-laptop> (raw)
In-Reply-To: <20231205155927.4b3b9151@gandalf.local.home>
On Tue, Dec 05, 2023 at 03:59:27PM -0500, Steven Rostedt wrote:
> On Sat, 2 Dec 2023 18:45:07 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
>
> > On Sat, 2 Dec 2023 14:24:26 -0800
> > "Paul E. McKenney" <paulmck@kernel.org> wrote:
> >
> > > > Note, the unlikely tracing is running on my production server v6.6.3.
> > > >
> > > > The above trace is from my test box with latest Linus's tree.
> > >
> > > Nice tool!!!
> >
> > Thanks! It's only been in the kernel since 2008 ;-)
> >
> > 1f0d69a9fc815 ("tracing: profile likely and unlikely annotations")
> >
> > >
> > > My kneejerk reaction is that that condition is suboptimal. Does the
> > > (untested) patch below help things?
> >
> > I'll give it a try on Monday.
> >
>
> This looks to have caused a difference. Although there's other RCU
> functions that need dealing with, but that's for when I have time to
> analyze all the places that have bad annotations.
>
>
> Anyway:
>
> correct incorrect % Function File Line
> ------- --------- - -------- ---- ----
> [..]
> 17924 0 0 rcu_softirq_qs tree.c 247
>
> Tested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Thank you very much, and I will apply this on my next rebase.
One of the disadvantages of userspace-free rcutorture testing...
Thanx, Paul
prev parent reply other threads:[~2023-12-05 22:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-01 20:49 [RCU] rcu_tasks_trace_qs(): trc_reader_special.b.need_qs value incorrect likely()? Steven Rostedt
2023-12-02 22:24 ` Paul E. McKenney
2023-12-02 23:45 ` Steven Rostedt
2023-12-05 20:59 ` Steven Rostedt
2023-12-05 22:01 ` Paul E. McKenney [this message]
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