From: Arnaldo Carvalho de Melo on
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
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