linux-kernel - Re: [PATCH] perf/x86: Fix overlap counter scheduling bug

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Message-ID: <20161214155940.GA9180@krava>
Date:   Wed, 14 Dec 2016 16:59:40 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Robert Richter <rric@...nel.org>,
        "Liang, Kan" <kan.liang@...el.com>,
        Andi Kleen <andi@...stfloor.org>, Jiri Olsa <jolsa@...nel.org>,
        Vince Weaver <vince@...ter.net>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH] perf/x86: Fix overlap counter scheduling bug

On Wed, Nov 09, 2016 at 04:51:53PM +0100, Peter Zijlstra wrote:

SNIP

> 
> As per a prior mail, the masks on the PMU in question are:
> 
>  0x01 - 0001
>  0x03 - 0011
>  0x0e - 1110
>  0x0c - 1100
> 
> But since all the masks that have overlap (0xe -> {0xc,0x3}) and (0x3 ->
> 0x1) are of heavier weight, it should all work out I think.
> 
> So yes, something like the below (removing the OVERLAP bit) looks like
> its sufficient.

Peter,
could you please take this one?

thanks,
jirka

> 
> ---
>  arch/x86/events/intel/uncore_snbep.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
> index 272427700d48..e6832be714bc 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -669,7 +669,7 @@ static struct event_constraint snbep_uncore_cbox_constraints[] = {
>  	UNCORE_EVENT_CONSTRAINT(0x1c, 0xc),
>  	UNCORE_EVENT_CONSTRAINT(0x1d, 0xc),
>  	UNCORE_EVENT_CONSTRAINT(0x1e, 0xc),
> -	EVENT_CONSTRAINT_OVERLAP(0x1f, 0xe, 0xff),
> +	UNCORE_EVENT_CONSTRAINT(0x1f, 0xe),
>  	UNCORE_EVENT_CONSTRAINT(0x21, 0x3),
>  	UNCORE_EVENT_CONSTRAINT(0x23, 0x3),
>  	UNCORE_EVENT_CONSTRAINT(0x31, 0x3),