linux-kernel - Re: [PATCH] perf tools: Do not fail on processing out of order event

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Date:	Thu, 27 Nov 2014 11:54:35 -0200
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <ak@...ux.intel.com>,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Matt Fleming <matt.fleming@...el.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH] perf tools: Do not fail on processing out of order event

Em Thu, Nov 27, 2014 at 01:54:16PM +0100, Jiri Olsa escreveu:
> On Thu, Nov 27, 2014 at 11:56:03AM +0100, Ingo Molnar wrote:
> 
> SNIP
> 
> > > > -		pr_oe_time(timestamp,      "out of order event");
> > > > +		pr_oe_time(timestamp,      "out of order event\n");
> > > >  		pr_oe_time(oe->last_flush, "last flush, last_flush_type %d\n",
> > > >  			   oe->last_flush_type);
> > > >  
> > > > -		/* We could get out of order messages after forced flush. */
> > > > -		if (oe->last_flush_type != OE_FLUSH__HALF)
> > > > -			return -EINVAL;
> > > > +		s->stats.nr_unordered_events++;
> > 
> > Btw., in the forced flush case we'll get out of order events that 
> > are 'expected'. Shouldn't we count them separately and not warn 
> > about them, or so?
> 
> hum, we warned about them anyway, we just did not fail processing..
> and the impact of both cases should be the same.. it's just at the
> forced flush we expected/allowed out of order events
> 
> so I think it's ok to share the same counter and warn about
> them the same way

Sure? See my other message, aren't those two kinds of reordering? I.e.
one that we can "fix" (aka reorder as part of a flush), one that we
can't?
 
> > 
> > > > +	if (session->stats.nr_unordered_events != 0) {
> > > > +		ui__warning("%u out of order events recorded.\n",
> > > > +			    session->stats.nr_unordered_events);
> > > > +	}
> > 
> > Nit: I'd suggest keeping the message printout on a single line:
> >  
> > 	if (session->stats.nr_unordered_events != 0) {
> > 		ui__warning("%u out of order events recorded.\n", session->stats.nr_unordered_events);
> > 
> > as IMHO the cure for this col80 linebreak checkpatch warning is 
> > worse than the disease! :-)
> 
> ok ;-)
> 
> > 
> > Barring those details:
> > 
> >   Acked-by: Ingo Molnar <mingo@...nel.org>
> 
> thanks,
> jirka
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