From: Steven Rostedt <rostedt@goodmis.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
Nicholas Mc Guire <der.herr@hofr.at>,
Joel Fernandes <agnel.joel@gmail.com>,
Greg Kroah-Hartman <greg@kroah.com>,
linux-rt-users@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
kernelnewbies <kernelnewbies@nl.linux.org>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: RFC on fixing mutex spinning on owner
Date: Thu, 17 Mar 2016 08:06:29 -0400 [thread overview]
Message-ID: <20160317080629.1af8f733@grimm.local.home> (raw)
In-Reply-To: <alpine.DEB.2.11.1603171214530.3978@nanos>
On Thu, 17 Mar 2016 12:16:11 +0100 (CET)
Thomas Gleixner <tglx@linutronix.de> wrote:
> On Thu, 17 Mar 2016, Peter Zijlstra wrote:
> > Also, maybe the tracer should measure the time from need_resched()
> > getting true until the next preemption point, instead of the entire time
> > preemption was disabled. Which would avoid the entire issue altogether.
>
> Well, that only gives you the information on a actual preemption, but not
> information about long preempt disabled regions which can cause a problem
> eventually.
>
Actually, I was thinking the reverse. If need_resched() is called and
is false, then do a reset of the preemption time. But if need_resched()
is true, then do nothing, as that would measure the total time preempt
disable was set and a task could not schedule.
Question is, should this be a hook and each location audited, or add
this to need_resched() itself?
-- Steve
next prev parent reply other threads:[~2016-03-17 12:06 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-16 23:22 RFC on fixing mutex spinning on owner Joel Fernandes
2016-03-16 23:35 ` Greg Kroah-Hartman
2016-03-16 23:38 ` Joel Fernandes
2016-03-17 2:17 ` Steven Rostedt
2016-03-17 5:35 ` Joel Fernandes
2016-03-17 12:08 ` Steven Rostedt
2016-03-17 7:36 ` Peter Zijlstra
2016-03-17 8:05 ` Nicholas Mc Guire
2016-03-17 10:18 ` Peter Zijlstra
2016-03-17 11:16 ` Thomas Gleixner
2016-03-17 12:06 ` Steven Rostedt [this message]
2016-03-17 12:13 ` Peter Zijlstra
2016-03-17 13:32 ` Thomas Gleixner
2016-03-17 15:36 ` Nicholas Mc Guire
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