From: Andi Kleen <andi@firstfloor.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Andi Kleen <andi@firstfloor.org>,
Peter Zijlstra <peterz@infradead.org>,
Jiri Olsa <jolsa@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
Jan Stancek <jstancek@redhat.com>
Subject: Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage!
Date: Mon, 21 Nov 2016 10:06:54 -0800 [thread overview]
Message-ID: <20161121180654.GV26852@two.firstfloor.org> (raw)
In-Reply-To: <20161121130115.2f0f38e7@gandalf.local.home>
> And a popf can be much more expensive than any of these. You should
> know, not all instructions are equal.
>
> Using perf, I've seen popf take up almst 30% of a function the size of
> this.
In any case it's a small fraction of the 600+ instructions which are currently
executed for every enabled trace point.
If ftrace was actually optimized code this would make some sense, but it
clearly isn't ...
-Andi
next prev parent reply other threads:[~2016-11-21 18:06 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-21 0:53 [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Jiri Olsa
2016-11-21 9:02 ` Paul E. McKenney
2016-11-21 9:43 ` Peter Zijlstra
2016-11-21 11:00 ` Paul E. McKenney
2016-11-21 9:28 ` Peter Zijlstra
2016-11-21 9:34 ` Jiri Olsa
2016-11-21 9:42 ` Peter Zijlstra
2016-11-21 11:22 ` Jiri Olsa
2016-11-21 11:31 ` Peter Zijlstra
2016-11-21 12:49 ` Jiri Olsa
2016-11-21 12:58 ` Peter Zijlstra
2016-11-21 14:15 ` Steven Rostedt
2016-11-21 14:37 ` Peter Zijlstra
2016-11-21 15:35 ` Borislav Petkov
2016-11-21 15:41 ` Peter Zijlstra
2016-11-21 16:06 ` Borislav Petkov
2016-11-29 13:16 ` Borislav Petkov
2016-11-29 13:59 ` Thomas Gleixner
2016-11-30 8:48 ` Borislav Petkov
2016-11-30 8:54 ` Thomas Gleixner
2016-11-30 9:07 ` Borislav Petkov
2016-11-30 9:14 ` Thomas Gleixner
2016-11-29 14:04 ` Jiri Olsa
2016-11-21 14:20 ` Steven Rostedt
2016-11-21 17:06 ` Andi Kleen
2016-11-21 17:18 ` Peter Zijlstra
2016-11-21 17:45 ` Andi Kleen
2016-11-21 18:01 ` Steven Rostedt
2016-11-21 18:06 ` Andi Kleen [this message]
2016-11-21 18:22 ` Steven Rostedt
2016-11-21 18:37 ` Andi Kleen
2016-11-21 19:06 ` Steven Rostedt
2016-11-21 19:15 ` Steven Rostedt
2016-11-21 20:44 ` Andi Kleen
2016-11-22 8:19 ` Paul E. McKenney
2016-11-22 14:39 ` Steven Rostedt
2016-11-22 19:05 ` Andi Kleen
2016-11-24 2:06 ` Steven Rostedt
2016-11-28 21:48 ` Andi Kleen
2016-11-28 22:46 ` Steven Rostedt
2016-11-28 23:10 ` Andi Kleen
2016-11-21 17:55 ` Steven Rostedt
2016-11-21 18:24 ` Steven Rostedt
2016-11-21 20:12 ` Paul E. McKenney
2017-02-23 12:24 ` Jiri Olsa
2017-02-23 17:11 ` Andi Kleen
2017-02-23 17:28 ` Peter Zijlstra
2017-02-23 17:56 ` Borislav Petkov
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