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RFC ARM: perf: support multiple PMUs

Srinidhi Kasagar linux-arm-kernel 1 version New

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Cover letter Fwd: [RFC PATCH 00/15] ARM: perf: support multiple PMUs

Hello Marc/Will,

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Quoted 6 lines

Subject: [RFC PATCH 00/15] ARM: perf: support multiple PMUs
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From: Mark Rutland <mark.rutland at arm.com<mailto:[email protected]>>
Date: Mon, Aug 15, 2011 at 7:12 PM
To: linux-arm-kernel at lists.infradead.org

[...]

Quoted 22 lines

System (AKA nest or uncore) PMUs exist on devices which are not affine to a single CPU. They usually cannot be directly associated with individual tasks and are asynchronous with respect to the current execution. Examples of devices which could have system PMUs include L2 cache controllers, GPUs and memory buses.

The following patch series refactors the ARM PMU backend, enabling new PMUs to reuse the existing code. This should allow for system PMUs to be supported in future. Further work will be required to get perf to fully understand system PMUs, but this provides something usable.

The framework is intended to be used by system PMUs which hang off core platform components (e.g. L2 cache, AXI bus). If a device is complex enough or separate enough from core functionality to have its own driver, it should implement its own PMU handling using the core perf API directly.

The first patch ("perf: provide PMU when initing events") is currently sitting in the tip tree, but as it's required for event initialization to function (and hence for the PMU to be usable), it's provided here for convenience.

Quoted 7 lines

The series is based on Will Deacon's perf-updates branch at:

       git://linux-arm.org/linux-2.6-wd.git perf-updates

An example driver using the framework (supporting the PMU present in L220/PL310 level 2 cache controllers) can be found at:

       git://linux-arm.org/linux-2.6-wd.git perf-l2x0-wip

Do you still maintain this tree? Looks it is empty. I'm wondering if we can make use of this to instrument the PMU counters of L2/pl310.

/srinidhi