[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1386404544.5673.88.camel@marge.simpson.net>
Date: Sat, 07 Dec 2013 09:22:24 +0100
From: Mike Galbraith <bitbucket@...ine.de>
To: Andi Kleen <andi@...stfloor.org>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org,
Andi Kleen <ak@...ux.intel.com>, lenb@...nel.org,
tglx@...utronix.de, peterz@...radead.org
Subject: Re: [PATCH] Trace idle entry and exit times
On Sat, 2013-12-07 at 06:20 +0100, Andi Kleen wrote:
> On Sat, Dec 07, 2013 at 05:57:32AM +0100, Mike Galbraith wrote:
> > On Fri, 2013-12-06 at 16:46 -0800, Andi Kleen wrote:
> > > From: Andi Kleen <ak@...ux.intel.com>
> > >
> > > This patch creates 4 new trace points: one at the beginning of idle,
> > > one before entering mwait, one after exiting mwait, and one after
> > > finishing the idle code. This is useful to trace down any
> > > additional latencies caused by the ever-growing idle code.
> > >
> > > Idle latencies are a common source of performance problems, so it's
> > > important to be able to measure them.
> >
> > You mean stuff like.. oh, say 60 cores doing zero work every 12ms
> > munching ~20% cpu?
>
> Well that one is obvious. I mean more the subtle problems.
Yeah, not subtle. SGI could use C2 as power supply stress tester.
-Mike
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists