linux-kernel - Re: [PATCH v2 0/12] perf/x86: implement HT leak workaround for SNB/IVB/HSW

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Message-ID: <CABPqkBTDz56a9Hoy04W6VmTG_FTOE72037D0tmnh+ntw+VW0ZQ@mail.gmail.com>
Date:	Tue, 21 Oct 2014 14:28:06 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	Jiri Olsa <jolsa@...hat.com>,
	"Liang, Kan" <kan.liang@...el.com>, Borislav Petkov <bp@...en8.de>,
	Maria Dimakopoulou <maria.n.dimakopoulou@...il.com>
Subject: Re: [PATCH v2 0/12] perf/x86: implement HT leak workaround for SNB/IVB/HSW

Peter,

On Tue, Oct 21, 2014 at 1:25 PM, Peter Zijlstra <peterz@...radead.org> wrote:
>
>
> lkml.kernel.org/r/CABPqkBRbst4sgpgE5O_VXt-CSC0VD=aP2KWA0e3Uy64tw7df3A@...l.gmail.com
>
> I missed that 3 lines if they were in here.
>
I did not put them in there because there is another problem.
If you partition the generic counters 2 and 2, then some CPUs will not
be able to measure some events.
Unfortunately, there is no way to partition the 4 counters such that
all the events can be measured by
each CPU. Some events or precise sampling requires counter 2 for
instance (like prec_dist).
That's why I did not put this fix in.
--
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