linux-kernel - Re: [PATCH V6 2/5] perf/x86/kvm: Avoid unnecessary work in guest filtering

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Date:   Mon, 4 Feb 2019 17:15:20 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Liang, Kan" <kan.liang@...ux.intel.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, tglx@...utronix.de,
        bp@...en8.de, mingo@...hat.com, ak@...ux.intel.com,
        eranian@...gle.com
Subject: Re: [PATCH V6 2/5] perf/x86/kvm: Avoid unnecessary work in guest
 filtering

On Mon, Feb 04, 2019 at 10:43:41AM -0500, Liang, Kan wrote:
> > --- a/arch/x86/events/intel/ds.c
> > +++ b/arch/x86/events/intel/ds.c
> > @@ -1628,6 +1628,7 @@ void __init intel_ds_init(void)
> >   	x86_pmu.bts  = boot_cpu_has(X86_FEATURE_BTS);
> >   	x86_pmu.pebs = boot_cpu_has(X86_FEATURE_PEBS);
> >   	x86_pmu.pebs_buffer_size = PEBS_BUFFER_SIZE;
> > +	x86_pmu.pebs_no_isolation = 1;
> 
> We will submit the Icelake support soon (probably next week).
> That will be a problem for Icelake.

We can have ICL set it to 0 explicitly, but explicitly setting it to 1
_11_ times is just silly.

Also, what perfmon version will ICL have? If it were to be 5 we could
key off of that.