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Date: Tue, 30 Jan 2018 19:52:12 +0100
From: Jiri Olsa <jolsa@redhat.com>
To: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: Stephane Eranian <eranian@google.com>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
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        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH V3 0/5] bugs fix for large PEBS mmap read and rdpmc read
Message-ID: <20180130185212.GA16806@krava>
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On Tue, Jan 30, 2018 at 11:48:18AM -0500, Liang, Kan wrote:

SNIP

> > > 
> > > The events in fixed mode could enable large PEBS. Events in freq mode should
> > > not enable large PEBS.
> > > I think that could be a problem if some events try to enable large PEBS,
> > > while others not.
> > > 
> > You only enable large PEBS if 100% of the events use fixed periods,
> > either via -c period
> > or because they all use individual period=p. The --no-period could
> > also be used to remove
> > the period for measurements where the period is not needed.
> 
> 
> Oh, right, the kernel has already guaranteed that.
> 	if (cpuc->n_pebs == cpuc->n_large_pebs) {
> 		threshold = ds->pebs_absolute_maximum -
> 			x86_pmu.max_pebs_events * x86_pmu.pebs_record_size;
> 	} else {
> 
> Sorry for the noise.
> 
> jirka's patch looks good to me.

cool, I'll post it later this week

thanks,
jirka