linux-kernel - Re: [PATCH v9 0/8] perf/amd/iommu: Enable multi-IOMMU support

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Date:   Wed, 15 Feb 2017 11:13:23 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        peterz@...radead.org, joro@...tes.org, mingo@...hat.com
Subject: Re: [PATCH v9 0/8] perf/amd/iommu: Enable multi-IOMMU support

On Tue, Feb 07, 2017 at 02:40:28AM -0600, Suravee Suthikulpanit wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> 
> This patch series modifies the existing IOMMU and Perf drivers to support
> systems with multiple IOMMUs by allocating an amd_iommu PMU per IOMMU instance.
> This allows users to specify performance events and filters separately for each
> IOMMU.
> 
> This has been tested on the new family17h-based server w/ multiple IOMMUs.

Ok, so far so good.

There's just one thing:

$ perf stat -e amd_iommu_X/Y

says <not supported> and only doing the system wide tracing with -a does
it count events.

So, lemme ask perf tool people, can we guys make the -a thing default
when detect that we're running only uncore events which all should need
-a anyway?

Otherwise people who, like me, don't know that, would try to do
measurements and see the <not supported> and wonder...

Lemme add some more people to CC.

-- 
Regards/Gruss,
    Boris.

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