From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>,
Russell King <linux@arm.linux.org.uk>,
Thomas Gleixner <tglx@linutronix.de>,
Aaron Tomlin <atomlin@redhat.com>, Ingo Molnar <mingo@redhat.com>,
Andrew Morton <akpm@osdl.org>,
Daniel Thompson <daniel.thompson@linaro.org>,
x86@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH v3 4/4] nmi_backtrace: generate one-line reports for idle cpus
Date: Tue, 22 Mar 2016 23:28:03 +0100 [thread overview]
Message-ID: <1714182.jSNjvC6qiX@vostro.rjw.lan> (raw)
In-Reply-To: <20160322173005.GT6344@twins.programming.kicks-ass.net>
On Tuesday, March 22, 2016 06:30:05 PM Peter Zijlstra wrote:
> On Tue, Mar 22, 2016 at 01:19:39PM -0400, Chris Metcalf wrote:
> > When doing an nmi backtrace of many cores, most of which are idle,
> > the output is a little overwhelming and very uninformative. Suppress
> > messages for cpus that are idling when they are interrupted and just
> > emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".
> >
> > We do this by grouping all the cpuidle code together into a new
> > .cpuidle.text section, and then checking the address of the
> > interrupted PC to see if it lies within that section.
> >
> > This commit suitably tags x86, arm64, and tile idle routines,
> > and only adds in the minimal framework for other architectures.
> >
> > Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
>
> For some reason I found a few CPUs using poll_idle().
>
> Rafael, when and why would that ever get selected as a useful idle
> state? When the predicted idle time is so short even C1 isn't worth it?
Yes, that's the case.
next prev parent reply other threads:[~2016-03-22 22:25 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20160307204317.GR6344@twins.programming.kicks-ass.net>
2016-03-16 17:02 ` [PATCH v2 0/4] improvements to the nmi_backtrace code Chris Metcalf
2016-03-16 17:02 ` Chris Metcalf
2016-03-16 17:02 ` [PATCH v2 4/4] nmi_backtrace: generate one-line reports for idle cpus Chris Metcalf
2016-03-16 17:02 ` Chris Metcalf
2016-03-16 18:46 ` kbuild test robot
2016-03-16 18:46 ` kbuild test robot
2016-03-21 15:38 ` Peter Zijlstra
2016-03-21 15:38 ` Peter Zijlstra
2016-03-21 15:46 ` Chris Metcalf
2016-03-21 15:46 ` Chris Metcalf
2016-03-21 15:42 ` Peter Zijlstra
2016-03-21 16:15 ` Chris Metcalf
2016-03-21 16:15 ` Chris Metcalf
2016-03-21 16:32 ` Peter Zijlstra
2016-03-21 17:12 ` Chris Metcalf
2016-03-21 17:12 ` Chris Metcalf
2016-03-21 17:17 ` Peter Zijlstra
2016-03-21 16:48 ` Peter Zijlstra
2016-03-21 21:49 ` Peter Zijlstra
2016-03-22 17:19 ` [PATCH v3 0/4] improvements to the nmi_backtrace code Chris Metcalf
2016-03-22 17:19 ` Chris Metcalf
2016-03-22 17:19 ` [PATCH v3 4/4] nmi_backtrace: generate one-line reports for idle cpus Chris Metcalf
2016-03-22 17:19 ` Chris Metcalf
2016-03-22 17:30 ` Peter Zijlstra
2016-03-22 22:28 ` Rafael J. Wysocki [this message]
2016-03-22 22:31 ` Rafael J. Wysocki
2016-03-22 22:45 ` Peter Zijlstra
2016-03-23 0:50 ` Rafael J. Wysocki
2016-03-23 7:53 ` Peter Zijlstra
2016-03-30 17:16 ` [PATCH v4 0/4] improvements to the nmi_backtrace code Chris Metcalf
2016-03-30 17:16 ` Chris Metcalf
2016-03-30 17:16 ` [PATCH v4 4/4] nmi_backtrace: generate one-line reports for idle cpus Chris Metcalf
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