* Re: Question: SMMUv3 PMU event aliasing
2021-11-08 12:41 ` Question: SMMUv3 PMU event aliasing John Garry
@ 2021-11-09 1:48 ` Leo Yan
2021-11-09 11:32 ` Robin Murphy
1 sibling, 0 replies; 3+ messages in thread
From: Leo Yan @ 2021-11-09 1:48 UTC (permalink / raw)
To: John Garry
Cc: linux-perf-users, linux-kernel,
linux-arm-kernel@lists.infradead.org
Hi John,
On Mon, Nov 08, 2021 at 12:41:33PM +0000, John Garry wrote:
[...]
> > 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.
Thanks for info. When send out the new patch, you are welcome to Cc
to me, I am glad to give a test on D06 board (its IIDR is zero, so
I need to tweak a bit in driver for IIDR :)).
Thanks,
Leo
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* Re: Question: SMMUv3 PMU event aliasing
2021-11-08 12:41 ` Question: SMMUv3 PMU event aliasing John Garry
2021-11-09 1:48 ` Leo Yan
@ 2021-11-09 11:32 ` Robin Murphy
1 sibling, 0 replies; 3+ messages in thread
From: Robin Murphy @ 2021-11-09 11:32 UTC (permalink / raw)
To: John Garry, Leo Yan, linux-perf-users, linux-kernel
Cc: linux-arm-kernel@lists.infradead.org
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/
>>
>> .
>>
>
>
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