From: Will Deacon <will@kernel.org>
To: Leo Yan <leo.yan@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Mike Leach <mike.leach@arm.com>,
James Clark <james.clark@linaro.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Tamas Petz <tamas.petz@arm.com>,
Tamas Zsoldos <tamas.zsoldos@arm.com>,
Michiel van Tol <michiel.vantol@arm.com>,
Dev Jain <dev.jain@arm.com>, David Hildenbrand <david@kernel.org>,
Yabin Cui <yabinc@google.com>,
coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org
Subject: Re: [PATCH 2/2] perf: arm_spe: Prefer large AUX mappings
Date: Mon, 10 Aug 2026 16:10:48 +0100 [thread overview]
Message-ID: <annp-BdTviQoH6vy@willie-the-truck> (raw)
In-Reply-To: <20260810-perf_aux_trace_large_granule-v1-2-03306c9339e3@arm.com>
On Mon, Aug 10, 2026 at 03:44:42PM +0100, Leo Yan wrote:
> Commit 18049c8cff9c ("perf/aux: Allocate non-contiguous AUX pages by
> default") made the AUX allocator use order-0 pages by default unless a
> PMU explicitly asks for contiguous allocations.
But that commit specifically calls out SPE as benefitting from
non-contiguous pages:
"For instance, ARM SPE and TRBE operate with virtual pages, and
Coresight ETR allocates a separate buffer. For these PMUs,
allocating contiguous AUX pages unnecessarily exacerbates memory
fragmentation. This fragmentation can prevent their use on
long-running devices."
so why doesn't passing PERF_PMU_CAP_AUX_PREFER_LARGE reintroduce the
problems that 18049c8cff9c was trying to solve?
Will
next prev parent reply other threads:[~2026-08-10 15:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-10 14:44 [PATCH 0/2] perf/arm: Prefer large AUX mappings for CoreSight and SPE Leo Yan
2026-08-10 14:44 ` [PATCH 1/2] coresight: perf: Prefer large AUX mappings Leo Yan
2026-08-10 14:44 ` [PATCH 2/2] perf: arm_spe: " Leo Yan
2026-08-10 15:10 ` Will Deacon [this message]
2026-08-10 17:41 ` Leo Yan
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