Messages in this thread | | | Date | Mon, 22 Feb 2016 22:24:57 -0700 | From | Alex Williamson <> | Subject | Re: [PATCH V4 5/6] perf/amd/iommu: Enable support for multiple IOMMUs |
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On Tue, 23 Feb 2016 12:12:42 +0700 Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> wrote:
> Hi > > On 02/22/2016 09:07 PM, Peter Zijlstra wrote: > > On Mon, Feb 22, 2016 at 03:00:31PM +0700, Suravee Suthikulpanit wrote: > >>> So I really don't have time to review new muck while I'm hunting perf > >>> core fail, but Boris made me look at this. > >>> > >>> This is crazy, if you have multiple IOMMUs then create an event per > >>> IOMMU, do _NOT_ fold them all into a single event. > >> > >> These are system-wide events, which are programmed on every IOMMU the same > >> way. I am not sure what you meant by creating an event per IOMMU. Do you > >> mean I should create internal per-IOMMU struct perf_event for each event? > > > > No, I meant to expose each IOMMU individually to userspace, as a > > separate device. > > > > Is there never a case to profile just one of the IOMMUs ? > > > > I see. That's definitely doable and simpler to implement. > > I was not sure if making users specify the IOMMU instance (e.g. > amd_iommu_0/<ev name> , amd_iommu_1/<ev_name>, ....) would be too > tedious. However, this would actually give users better control of the > performance events, which is a good trade-off. I think it is acceptable. > > I'll make the change and send this out in V5.
We already expose individual IOMMU hardware units in /sys/class/iommu/, you might consider trying to match the names there for the convenience of the user. Looks like we use ivhd%d for AMD. Thanks,
Alex
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