Messages in this thread | | | Subject | Re: [PATCH V4 5/6] perf/amd/iommu: Enable support for multiple IOMMUs | From | Suravee Suthikulpanit <> | Date | Tue, 23 Feb 2016 16:56:22 +0700 |
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On 02/23/2016 12:24 PM, Alex Williamson wrote: > 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 >
Hm, the PMU for AMD IOMMU is currently shown as /sys/device/amd_iommu. I am not sure if /sys/device/ivhd[0|1|...] would be obvious to users that IVHD is really the AMD IOMMU.
Suravee
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