linux-kernel - RE: [PATCH V8 8/8] perf tools: handle PERF_RECORD_LOST

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Date:	Thu, 7 May 2015 14:17:13 +0000
From:	"Liang, Kan" <kan.liang@...el.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	"peterz@...radead.org" <peterz@...radead.org>,
	"mingo@...nel.org" <mingo@...nel.org>,
	"acme@...radead.org" <acme@...radead.org>,
	"eranian@...gle.com" <eranian@...gle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH V8 8/8] perf tools: handle PERF_RECORD_LOST_SAMPLES



> 
> On Wed, May 06, 2015 at 03:33:54PM -0400, Kan Liang wrote:
> > From: Kan Liang <kan.liang@...el.com>
> >
> > This patch modified the perf tool to handle the new RECORD type,
> > PERF_RECORD_LOST_SAMPLES.
> > The number of lost-sample events is stored in
> > .nr_events[PERF_EVENT_LOST_SAMPLES]. While the exact number of
> samples
> > which the kernel dropped is stored in total_lost_samples.
> > When the percentage of dropped samples is greater than 5%, a warning
> > will be sent out.
> 
> That's nice. Would be good to also print this in perf report --stdio output
> (without -D), like the samples are.
>

OK, I will do it.

> Could you please do the same for the normal PERF_RECORD_LOST too?
> There we don't have a exact percentage, but at least could count the lost
> events too. This can be a separate patch of course, doesn't need to be tied
> to this patchkit.

I think current perf tool already did that.
It will print warning for any lost. 
Is this what you want?

	if (session->tool->lost == perf_event__process_lost &&
	    stats->nr_events[PERF_RECORD_LOST] != 0) {
		ui__warning("Processed %d events and lost %d chunks!\n\n"
			    "Check IO/CPU overload!\n\n",
			    stats->nr_events[0],
			    stats->nr_events[PERF_RECORD_LOST]);
	}

Thanks,
Kan
> 
> 
> -Andi
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