Hi Greg,
Following the conversation with Marc, we discovered that an important fix for ARM PMU is not backported to 4.14.y tree, it affects counter value and give out nonsensical result.
Can you please include the following commit? ``` commit 3cce50dfec4a5b0414c974190940f47dd32c6dee Author: Suzuki K Poulose suzuki.poulose@arm.com Date: Tue Jul 10 09:58:03 2018 +0100
arm64: perf: Disable PMU while processing counter overflows
The arm64 PMU updates the event counters and reprograms the counters in the overflow IRQ handler without disabling the PMU. This could potentially cause skews in for group counters, where the overflowed counters may potentially loose some event counts, while they are reprogrammed. To prevent this, disable the PMU while we process the counter overflows and enable it right back when we are done.
This patch also moves the PMU stop/start routines to avoid a forward declaration.
Suggested-by: Mark Rutland mark.rutland@arm.com Cc: Will Deacon will.deacon@arm.com Acked-by: Mark Rutland mark.rutland@arm.com Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com Signed-off-by: Will Deacon will.deacon@arm.com ```
For more details:
https://lists.cs.columbia.edu/pipermail/kvmarm/2021-June/047471.html
Regards, Aman Priyadarshi
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