linux-kernel - Re: [patch 9/9] pref: session: Break event ordering when timestamps are missing

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Message-ID: <alpine.LFD.2.00.1012091455590.2653@localhost6.localdomain6>
Date:	Thu, 9 Dec 2010 14:58:10 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Ian Munsie <imunsie@....ibm.com>
cc:	LKML <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [patch 9/9] pref: session: Break event ordering when timestamps
 are missing

On Thu, 9 Dec 2010, Ian Munsie wrote:
> Excerpts from Thomas Gleixner's message of Tue Dec 07 12:49:04 UTC 2010:
> > Allow the session client to specify that event ordering should be
> > stopped when not all events have time stamps.
> 
> >  	/* These events are processed right away */
> >  	switch (event->header.type) {
> >  	case PERF_RECORD_HEADER_ATTR:
> > -		return ops->attr(event, session);
> > +		/* This updates session->sample_id_all */
> > +		ret = ops->attr(event, session);
> > +		/* Break ordering if sample_id_all is false */
> > +		if (ops->ordering_requires_timestamps &&
> > +		    ops->ordered_samples && !session->sample_id_all) {
> > +			session->ordered_samples.next_flush = ULLONG_MAX;
> > +			flush_sample_queue(session, ops);
> > +			ops->ordered_samples = false;
> > +		}
> > +		return ret;
> Since the fall back isn't triggered, not only are COMM and MMAP events
> processed first (from patch 2 in this series), but EXIT will as well,
> which causes no userspace events to be attributed.

So we need to check this in every event processing path? Or do we have
for this kind of processing some other method which allows us to
disable the ordered_samples bit once ?

Thanks,

	tglx
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