linux-kernel - Re: [PATCH v3 0/5] perf: arm_spe: Add format option for discard mode

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Message-ID: <Z4UnIH8SXQC7kGXL@x1>
Date: Mon, 13 Jan 2025 11:45:52 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Will Deacon <will@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org,
	irogers@...gle.com, yeoreum.yun@....com, mark.rutland@....com,
	namhyung@...nel.org, James Clark <james.clark@...aro.org>,
	catalin.marinas@....com, kernel-team@...roid.com, robh@...nel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	John Garry <john.g.garry@...cle.com>,
	Mike Leach <mike.leach@...aro.org>, Leo Yan <leo.yan@...ux.dev>,
	Graham Woodward <graham.woodward@....com>,
	Michael Petlan <mpetlan@...hat.com>,
	Veronika Molnarova <vmolnaro@...hat.com>,
	Thomas Richter <tmricht@...ux.ibm.com>,
	Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH v3 0/5] perf: arm_spe: Add format option for discard mode

On Fri, Jan 10, 2025 at 04:22:48PM +0000, Will Deacon wrote:
> On Wed, 08 Jan 2025 14:28:55 +0000, James Clark wrote:
> > Discard mode (Armv8.6) is a way to enable SPE related PMU events without
> > the overhead of recording any data. Add a format option, tests and docs
> > for it.
> > 
> > In theory we could make the driver drop calls to allocate the aux buffer
> > when discard mode is enabled. This would give a small memory saving,
> > but I think there is potential to interfere with any tools that don't
> > expect this so I left the aux allocation untouched. Even old tools that
> > don't know about discard mode will be able to use it because we publish
> > the format option. Not allocating the aux buffer will have to be added
> > to tools which I've done in Perf.
> > 
> > [...]
> 
> Applied driver and docs patches to will (for-next/perf), thanks!

Picked the rest and added it to perf-tools-next,

Thanks,

- Arnaldo
 
> [1/5] perf: arm_spe: Add format option for discard mode
>       https://git.kernel.org/will/c/d28d95bc63cb
> [2/5] perf docs: arm_spe: Document new discard mode
>       https://git.kernel.org/will/c/ba113ecad81a
> 
> Cheers,
> -- 
> Will
> 
> https://fixes.arm64.dev
> https://next.arm64.dev
> https://will.arm64.dev