linux-kernel - Re: [PATCH v7 7/7] perf/amd/iommu: Enable support for multiple IOMMUs

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Message-ID: <6db9d730-b927-5a21-877c-fabb60b66bfe@amd.com>
Date:   Fri, 13 Jan 2017 17:24:01 +0700
From:   Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
To:     Borislav Petkov <bp@...en8.de>
CC:     <linux-kernel@...r.kernel.org>, <iommu@...ts.linux-foundation.org>,
        <joro@...tes.org>, <peterz@...radead.org>, <mingo@...hat.com>
Subject: Re: [PATCH v7 7/7] perf/amd/iommu: Enable support for multiple IOMMUs

Boris,

On 1/13/17 00:52, Borislav Petkov wrote:
> On Mon, Jan 09, 2017 at 09:33:47PM -0600, Suravee Suthikulpanit wrote:
>> This patch adds multi-IOMMU support for perf by exposing
>> an AMD IOMMU PMU for each IOMMU found in the system via:
>>
>>   /sys/device/amd_iommu_x     /* where x is the IOMMU index. */
> Straight into the top-level devices hierarchy?
>
> Why not add a proper hierarchy to
>
> /sys/devices/system/iommu/ ...
>
> ?
>
> Jörg, don't you have a sane iommu hierarchy already in sysfs?
>

IIUC, Perf tools looks at the /sys/devices/xxxxx to identify availalble PMUs.
Are you planning to have perf tools look at /sys/devices/system/iommu/xxx instead?

Suravee