linux-kernel - Re: [PATCH 1/2] perf session: Add option to copy events when queueing

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Date:	Thu, 18 Sep 2014 14:29:28 -0600
From:	David Ahern <dsahern@...il.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Alexander Yarygin <yarygin@...ux.vnet.ibm.com>
CC:	linux-kernel@...r.kernel.org,
	Christian Borntraeger <borntraeger@...ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
	Mike Galbraith <efault@....de>,
	Namhyung Kim <namhyung.kim@....com>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 1/2] perf session: Add option to copy events when queueing

On 9/18/14, 2:21 PM, David Ahern wrote:
> On 9/18/14, 12:53 PM, Arnaldo Carvalho de Melo wrote:
>> If nobody objects I'll merge this patch, as it fixes problems, but I
>> wonder if the best wouldn't be simply not calling
>> perf_evlist__mmap_consume() till the last event there is in fact
>> consumed... I.e. as we _really_ consume the events, we remove it from
>> there.
>>
>> Instead of consuming the event at perf_tool->sample() time, we would
>> do it at perf_tool->finished_round(), would that be feasible? Has anyone
>> tried this?
>
> Hmmm... haven't tried this.  Conceptually it should work - at least
> nothing comes to mind at the moment.

Upon further review ...

Alex you might want to try this first. Malloc and copy of all events is 
going to bring some serious overhead. Can avoid that if consuming the 
event in finished_round works.

David
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