linux-kernel - Re: [PATCH v1 0/4] perf: add ability to sample interrupted machine state

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Date:	Wed, 09 Jul 2014 17:26:20 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu,
	ak@...ux.intel.com, jolsa@...hat.com, acme@...hat.com
Subject: Re: [PATCH v1 0/4] perf: add ability to sample interrupted machine state

Hi Stephane,

On Wed,  9 Jul 2014 00:15:55 +0200, Stephane Eranian wrote:
> This short patch series add the ability to sample the interrupted
> machine state for each hardware sample. This is useful to analyze
> the state after certain events, for instance for function value
> profiling after a call instruction.
>
> The patch extends the interface with a new PERF_SAMPLE_REGS_INTR 
> smaple_type flag. The register to sample can be named in the
> sample_regs_intr bitmask for each event. The name and bit
> position for each register is architecture dependent and
> provided, just like for PERF_SAMPLE_REGS_USER by asm/perf_regs.h.
>
> The support is similar to PERF_SAMPLE_REGS_USER.
>
> On Intel x86, the series includes support for capturing the
> PEBS state as well. When precise sampling is used, the interrupted
> state is collect from the PEBS records, at least partially.
> The PEBS machine state is a subset of the machine state.
>
> The series provides access to this new feature in perf record
> with the -I option. It is possible to display the sampled
> register values using perf report -D.
>
> This patch series is the fundation for a future series adding
> function value profiling.

Probably a silly question: what is the function value profiling?

Anyway, I'll try to review it tomorrow. :)

Thanks,
Namhyung


>
> Stephane Eranian (4):
>   perf: add ability to sample machine state on interrupt
>   perf/x86: add support for sampling PEBS machine state registers
>   perf tools: add core support for sampling intr machine state regs
>   perf record: add new -I option to sample interrupted machine state
>
>  arch/x86/kernel/cpu/perf_event_intel_ds.c |   19 +++++++++++++
>  include/linux/perf_event.h                |    7 +++--
>  include/uapi/linux/perf_event.h           |   14 ++++++++-
>  kernel/events/core.c                      |   44 +++++++++++++++++++++++++++--
>  tools/perf/builtin-record.c               |    2 ++
>  tools/perf/perf.h                         |    1 +
>  tools/perf/util/event.h                   |    7 +++++
>  tools/perf/util/evsel.c                   |   23 ++++++++++++++-
>  tools/perf/util/session.c                 |   26 +++++++++++++++++
>  9 files changed, 137 insertions(+), 6 deletions(-)
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