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From: Jiri Olsa <jolsa@redhat.com>
To: David Carrillo-Cisneros <davidcc@google.com>
Cc: linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Wang Nan <wangnan0@huawei.com>, Andi Kleen <ak@linux.intel.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Stephane Eranian <eranian@google.com>,
	Paul Turner <pjt@google.com>
Subject: Re: [PATCH] perf/stat: fix bug in handling events in error state
Date: Thu, 13 Apr 2017 10:28:15 +0200	[thread overview]
Message-ID: <20170413082815.GC4784@krava> (raw)
In-Reply-To: <20170412182301.44406-1-davidcc@google.com>

On Wed, Apr 12, 2017 at 11:23:01AM -0700, David Carrillo-Cisneros wrote:
> From: Stephane Eranian <eranian@google.com>
> 
> (This is a patch has been sitting in the Intel CQM/CMT driver series
>  for a while, despite not depend on it. Sending it now independently
>  since the series is being discarded.)
> 
> When an event is in error state, read() returns 0
> instead of sizeof() buffer. In certain modes, such
> as interval printing, ignoring the 0 return value
> may cause bogus count deltas to be computed and
> thus invalid results printed.
> 
> This patch fixes this problem by modifying read_counters()
> to mark the event as not scaled (scaled = -1) to force
> the printout routine to show <NOT COUNTED>.
> 
> Signed-off-by: Stephane Eranian <eranian@google.com>
> Reviewed-by: David Carrillo-Cisneros <davidcc@google.com>

Acked-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

  reply	other threads:[~2017-04-13  8:28 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-12 18:23 [PATCH] perf/stat: fix bug in handling events in error state David Carrillo-Cisneros
2017-04-13  8:28 ` Jiri Olsa [this message]
2017-04-17  8:34 ` [tip:perf/core] perf stat: Fix " tip-bot for Stephane Eranian

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