Messages in this thread | | | Date | Tue, 9 Nov 2021 11:32:04 +0000 | Subject | Re: Question: SMMUv3 PMU event aliasing | From | Robin Murphy <> |
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On 2021-11-08 12:41, John Garry wrote: > On 08/11/2021 12:19, Leo Yan wrote: >> Hi John, >> >> [ + mailing list ] > > Hi Leo, > >> >> I'd like to confirm the latest upstream status for SMMUv3 PMU event >> aliasing. >> >> I see the patch set v6 of "perf pmu-events: Support event aliasing for >> system PMUs" [1] has been landed on the mainline kernel, and as an >> example, imx8mm DDR PMU has been supported as system PMU [2]. >> >> On the other hand, I can see patch set 5 contains the SMMUv3 PMU event >> aliasing with patch "perf vendor events arm64: Add Architected events >> smmuv3-pmcg.json" [3], but this patch was left out in patch set 6 and >> it's never landed on the mainline kernel. >> >> Could you share current status (or plan) for upstreaming SMMUv3 PMU >> event alias? Or if there have any block issue to prevent merging the >> changes in the mainline kernel? > > This feature should be supported in the SMMUv3 PMU kernel driver and > perf tool. > > However it relies on the SMMU PMU identifier sysfs file to work. This > relies on SMMU_PMCG_IIDR being set, which is introduced latest spec, > which not much HW will support yet - see commit 2c255223362e. In theory > we don't need that for the fixed, non-IMPDEF events, but I did not > complicate perf tool with that mixed support. > > That's the reason for which I paused smmuv3-pmcg.json upstream in [3]. I > will revive that for new gen HW when concrete IMPDEF events known and > shared.
FWIW, imp-def-events are readily available for the existing Arm implementations[1][2], and annoyingly we could trivially synthesise an IIDR value from their imp-def PIDR registers if only we knew that that was valid to do in the first place. I feel tempted now to resurrect Jean-Philippe's DT binding and have a quick hack at that, then maybe a much longer think about how to attempt it for IORT...
Cheers, Robin.
[1] https://developer.arm.com/documentation/100310/0202/Functional-description/Operation/Performance-Monitoring-Unit [2] https://developer.arm.com/documentation/101542/0001/Functional-description/Operation/Performance-Monitoring-Unit
> > Thanks, > John > >> >> Thanks for your help! >> >> Leo >> >> [1] >> https://lore.kernel.org/lkml/1607080216-36968-1-git-send-email-john.garry@huawei.com/ >> >> [2] pmu-events/arch/arm64/freescale/imx8mm/sys/ddrc.json >> [3] >> https://lore.kernel.org/lkml/1604666153-4187-6-git-send-email-john.garry@huawei.com/ >> >> . >> > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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