Messages in this thread | | | Date | Sat, 11 Feb 2017 21:41:33 +0100 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH] perf/stat: Add --disable-hwdt |
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* Borislav Petkov <bp@alien8.de> wrote:
> On Sat, Feb 11, 2017 at 06:59:10PM +0100, Ingo Molnar wrote: > > So I checked the perf-list manpage and it didn't tell me much about how to disable > > the NMI watchdog. > > Oh, it is buried there: > > " > EVENT GROUPS > ------------ > > ... > > > Globally pinned events can limit the number of counters available for > other groups. On x86 systems, the NMI watchdog pins a counter by default. > The nmi watchdog can be disabled as root with > > echo 0 > /proc/sys/kernel/nmi_watchdog" > > > How about a more proactive hint, something like: > > > > To disable the NMI watchdog permanently, do: > > Why permanently? We want it to run and be disabled around the > measurement only. Anyway, here's something more to the point:
> + if (print_free_counters_hint) > + fprintf(output, > +"Some events weren't counted. Try disabling the NMI watchdog:\n" > +" echo 0 > /proc/sys/kernel/nmi_watchdog\n" > +" perf stat ...\n" > +" echo 1 > /proc/sys/kernel/nmi_watchdog\n"); > }
Ok, looks good to me!
Acked-by: Ingo Molnar <mingo@kernel.org>
Thanks,
Ingo
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