linux-kernel - RE: [PATCH V7 3/6] perf, x86: handle multiple records in PEBS buffer

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Date:	Tue, 5 May 2015 16:36:51 +0000
From:	"Liang, Kan" <kan.liang@...el.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	"mingo@...nel.org" <mingo@...nel.org>,
	"acme@...radead.org" <acme@...radead.org>,
	"eranian@...gle.com" <eranian@...gle.com>,
	"andi@...stfloor.org" <andi@...stfloor.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH V7 3/6] perf, x86: handle multiple records in PEBS buffer



> On Tue, May 05, 2015 at 03:07:23PM +0200, Peter Zijlstra wrote:
> > On Mon, Apr 20, 2015 at 04:07:47AM -0400, Kan Liang wrote:
> > > From: Yan, Zheng <zheng.z.yan@...el.com>
> > > +static void perf_log_lost(struct perf_event *event) {
> > > +	struct perf_output_handle handle;
> > > +	struct perf_sample_data sample;
> > > +	int ret;
> > > +
> > > +	struct {
> > > +		struct perf_event_header	header;
> > > +		u64				id;
> > > +		u64				lost;
> > > +	} lost_event = {
> > > +		.header = {
> > > +			.type = PERF_RECORD_LOST,
> > > +			.misc = 0,
> > > +			.size = sizeof(lost_event),
> > > +		},
> > > +		.id		= event->id,
> > > +		.lost		= 1,
> > > +	};
> > > +
> > > +	perf_event_header__init_id(&lost_event.header, &sample,
> event);
> > > +
> > > +	ret = perf_output_begin(&handle, event,
> > > +				lost_event.header.size);
> > > +	if (ret)
> > > +		return;
> > > +
> > > +	perf_output_put(&handle, lost_event);
> > > +	perf_event__output_id_sample(event, &handle, &sample);
> > > +	perf_output_end(&handle);
> > > +}
> >
> > RECORDs are generic, and should live in the core code.
> >
> > Also, you should introduce this RECORD in a separate patch.
> 
> On that, this is lacking a RECORD definition in
> include/uapi/linux/perf_event.h:perf_event_type

The PERF_RECORD_LOST already defined in  perf_event_type.
Are you suggesting to add a new dedicated RECORD type, like PERF_RECORD_COLLISION?
Or update the definition about PERF_RECORD_LOST?

Thanks,
Kan

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