Re: [PATCH 1/1] Change IBS PMU to use perf_hw_context

From: Ingo Molnar
Date: Sun Dec 16 2012 - 04:04:15 EST

* suravee.suthikulpanit@xxxxxxx <suravee.suthikulpanit@xxxxxxx> wrote:

> From: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> Currently, the AMD IBS PMU initialize pmu.task_ctx_nr to
> perf_invalid_context which only allows IBS to be running only
> in system-wide mode (e.g. perf record -a). IBS hardware is
> available in each core and should be per-context. This patch
> modifies the task_ctx_nr to use the perf_hw_context (default)
> instead.

I'm wondering how extensively was it tested/verified that it's
safe to enable IBS in per context mode as well, and that the
profiling results are precise and accurate?

We never used the IBS hardware in this fashion before, so some
extra care is prudent - and traces of that extra care should be
visible in the changelog as well.


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