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 12:12:42 +0700 |
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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.
Thanks, Suravee
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