linux-kernel - Re: [PATCH v2 0/4] remove unnecessary IPI reading uncore events

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Date:	Wed, 10 Aug 2016 13:30:34 -0500
From:	Nilay Vaish <nilayvaish@...il.com>
To:	David Carrillo-Cisneros <davidcc@...gle.com>
Cc:	Linux Kernel list <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andi Kleen <ak@...ux.intel.com>,
	Kan Liang <kan.liang@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Vegard Nossum <vegard.nossum@...il.com>,
	Paul Turner <pjt@...gle.com>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v2 0/4] remove unnecessary IPI reading uncore events

On 6 August 2016 at 22:12, David Carrillo-Cisneros <davidcc@...gle.com> wrote:
> This patch series adds a new flag to the struct perf_event
> (and a flag field to store it) to allow a PMU to tag a CPU or
> cgroup event as readable from any CPU in the same package and not
> just the CPU where the is currently active.
>
> This capability is used with uncore events to potentially avoid
> an unnecessary IPI when executing perf_event_read.
>
> A previous version of this change was introduced in the last Intel's
> CQM/CMT driver series (under review), but now we present it separately
> here since it is also useful for other uncore events.
>
> The next version of Intel CQM/CMT will add 3 new flags that use
> the pmu_event_flags field (added in patch 03 in this series).
>
> Patch 02 generalizes event->group_flags so that new flags can use it
> in a similar way that PERF_GROUP_SOFTWARE was used.
>
> Patches rebased at peterz/queue/perf/core
>
> Changes in v2:
>   - Change logic to use event->group_flags instead of individually
>   testing sibling in perf_event_read.
>   - Remove erroneous read of inactive events.
>
> David Carrillo-Cisneros (4):
>   perf/core: check return value of perf_event_read IPI
>   perf/core: generalize event->group_flags
>   perf/core: introduce PMU_EV_CAP_READ_ACTIVE_PKG
>   perf/x86: use PMUEF_READ_CPU_PKG in uncore events
>
>  arch/x86/events/intel/rapl.c       |  2 ++
>  arch/x86/events/intel/uncore.c     |  2 ++
>  arch/x86/events/intel/uncore_snb.c |  2 ++
>  include/linux/perf_event.h         | 21 +++++++++++----
>  kernel/events/core.c               | 52 +++++++++++++++++++++++++-------------
>  5 files changed, 57 insertions(+), 22 deletions(-)
>
> --
> 2.8.0.rc3.226.g39d4020
>

Reviewed-by: Nilay Vaish <nilayvaish@...il.com>