linux-kernel - Re: [PATCH 4/6 -tip] perf_counter: Add Generalized Hardware interrupt support for AMD

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Date:	Sun, 5 Jul 2009 03:11:23 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Jaswinder Singh Rajput <jaswinder@...nel.org>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arjan van de Ven <arjan@...radead.org>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	Anton Blanchard <anton@...ba.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	x86 maintainers <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH 4/6 -tip] perf_counter: Add Generalized Hardware
	interrupt support for AMD


* Jaswinder Singh Rajput <jaswinder@...nel.org> wrote:

> On Sat, 2009-07-04 at 12:22 +0200, Ingo Molnar wrote:
> > * Jaswinder Singh Rajput <jaswinder@...nel.org> wrote:
> > 
> > > On Wed, 2009-07-01 at 13:24 +0200, Ingo Molnar wrote:
> > > > * Jaswinder Singh Rajput <jaswinder@...nel.org> wrote:
> > > > 
> > > > > 
> > > > > $ ./perf stat -e interrupts -e masked -e int-pending-mask-cycles -- ls -lR /usr/include/ > /dev/null
> > > > > 
> > > > >  Performance counter stats for 'ls -lR /usr/include/':
> > > > > 
> > > > >             377  interrupts
> > > > >        53429936  int-mask-cycles
> > > > >            1119  int-pending-mask-cycles
> > > > > 
> > > > >     0.371457539  seconds time elapsed
> > > > 
> > > > Agreed, this is another useful generalization - and the 'cycles 
> > > > pending' metrics are not retrievable via any software means.
> > > > 
> > > > We could and should probably add a software counter for hardirqs 
> > > > as wel. That would allow the vector/irqnr information to be 
> > > > passed in, and it would allow architectures without irq metrics 
> > > > in the PMU to have this counter too.
> > > > 
> > > 
> > > Please let me know that addition of software counter will be 
> > > in this patch or we can do it incrementally after this patch.
> > 
> > It should be in this series. That way we can cross-check whether 
> > the soft counts and the hard counts match up and find potential 
> > bugs that way, etc.
> > 
> 
> You want to cross check performance counter events ?

Yes. The events are also more complete if we add per IRQ source 
counts as well, not just summary counts.

	Ingo
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