linux-kernel - [PATCH 0/2] perf,coresight: Reduce fragmentation with non-contiguous AUX pages for cs

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Message-ID: <20250421215818.3800081-1-yabinc@google.com>
Date: Mon, 21 Apr 2025 14:58:16 -0700
From: Yabin Cui <yabinc@...gle.com>
To: Suzuki K Poulose <suzuki.poulose@....com>, Mike Leach <mike.leach@...aro.org>, 
	James Clark <james.clark@...aro.org>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Peter Zijlstra <peterz@...radead.org>, 
	Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>, 
	Adrian Hunter <adrian.hunter@...el.com>, Liang Kan <kan.liang@...ux.intel.com>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org, 
	Yabin Cui <yabinc@...gle.com>
Subject: [PATCH 0/2] perf,coresight: Reduce fragmentation with non-contiguous
 AUX pages for cs_etm

Hi perf maintainers,
Hi coresight maintainers,

This patch set (2 patches) addresses memory fragmentation caused by
contiguous AUX buffer allocation for the cs_etm PMU on Android.

The cs_etm PMU doesn't need contiguous AUX pages, yet perf always allocates
contiguous AUX pages based on aux_watermark. So repeated use of cs_etm
with large buffers leads to memory fragmentation, negatively impacting
other processes.

This solution introduces PERF_PMU_CAP_AUX_NON_CONTIGUOUS_PAGES to allow
cs_etm to request non-contiguous AUX buffers, avoiding high-order page
allocations and reducing fragmentation.

This aims to reduce memory fragmentation for Android devices when using
cs_etm. Your review is appreciated.

Thanks,
Yabin

Yabin Cui (2):
  perf: Allow non-contiguous AUX buffer pages via PMU capability
  coresight: etm-perf: Add AUX_NON_CONTIGUOUS_PAGES to cs_etm PMU

 drivers/hwtracing/coresight/coresight-etm-perf.c | 3 ++-
 include/linux/perf_event.h                       | 1 +
 kernel/events/ring_buffer.c                      | 6 ++++++
 3 files changed, 9 insertions(+), 1 deletion(-)

-- 
2.49.0.805.g082f7c87e0-goog