From: Arnaldo Carvalho de Melo <acme@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: a.p.zijlstra@chello.nl, paulus@samba.org, mingo@elte.hu,
linux-kernel@vger.kernel.org
Subject: Re: perf can't keep up with mmap data
Date: Mon, 19 Jul 2010 12:04:33 -0300 [thread overview]
Message-ID: <20100719150433.GB5222@ghostprotocols.net> (raw)
In-Reply-To: <20100719074813.GA418@lst.de>
Em Mon, Jul 19, 2010 at 09:48:13AM +0200, Christoph Hellwig escreveu:
> When running current -tip perf in my 32-bit x86 kvm guest I get lots
> of messages like:
>
> WARNING: failed to keep up with mmap data.
>
> when starting perf top, and still quite a few everytime it refreshes the
> display.
Should be better reported, probably with a message suggesting to use:
perf top -r RTPRIO
or to reduce the sampling frequency:
perf top -F 500
to have:
PerfTop: 287 irqs/sec kernel:40.8% exact: 0.0% [500Hz cycles], (all, 2 CPUs)
Instead of the default:
PerfTop: 35 irqs/sec kernel:25.7% exact: 0.0% [1000Hz cycles], (all, 2 CPUs)
- Arnaldo
parent reply other threads:[~2010-07-19 15:04 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20100719074813.GA418@lst.de>]
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