linux-kernel - Re: [PATCH 2/4] perf/x86: Fix period for non sampling events

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Message-ID: <20170103094059.GC3093@worktop>
Date:   Tue, 3 Jan 2017 10:40:59 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andi Kleen <andi@...stfloor.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Vince Weaver <vince@...ter.net>
Subject: Re: [PATCH 2/4] perf/x86: Fix period for non sampling events

On Wed, Dec 28, 2016 at 02:31:04PM +0100, Jiri Olsa wrote:
> When in counting mode we setup the counter with the
> longest possible period and read the value with read
> syscall.
> 
> We also still setup the PMI to be triggered when such
> counter overflow to reconfigure it.
> 
> We also get PEBS interrupt if such counter has precise_ip
> set (which makes no sense, but it's possible).

I think we should reject non sampling pebs events, as you say they make
no sense what so ever.