linux-kernel - [PATCH 4/4] perf docs: Update SPE doc to include default instructions group

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Message-Id: <20250908-james-perf-spe-period-v1-4-7ccd805af461@linaro.org>
Date: Mon, 08 Sep 2025 13:10:21 +0100
From: James Clark <james.clark@...aro.org>
To: John Garry <john.g.garry@...cle.com>, Will Deacon <will@...nel.org>, 
 Mike Leach <mike.leach@...aro.org>, Leo Yan <leo.yan@...ux.dev>, 
 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>, 
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
 Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>, 
 Adrian Hunter <adrian.hunter@...el.com>, George Wort <George.Wort@....com>, 
 Graham Woodward <Graham.Woodward@....com>, Ben Gainey <Ben.Gainey@....com>, 
 Michael Williams <Michael.Williams@....com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org, 
 linux-kernel@...r.kernel.org, James Clark <james.clark@...aro.org>
Subject: [PATCH 4/4] perf docs: Update SPE doc to include default
 instructions group

The instructions group is now generated by default so update the doc to
reflect this. Also explain the period/downsampling mechanism in more
detail.

Signed-off-by: James Clark <james.clark@...aro.org>
---
 tools/perf/Documentation/perf-arm-spe.txt | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/tools/perf/Documentation/perf-arm-spe.txt b/tools/perf/Documentation/perf-arm-spe.txt
index 37afade4f1b2..cda8dd47fc4d 100644
--- a/tools/perf/Documentation/perf-arm-spe.txt
+++ b/tools/perf/Documentation/perf-arm-spe.txt
@@ -191,14 +191,20 @@ groups:
   36 branch
   0 remote-access
   900 memory
+  1800 instructions
 
 The arm_spe// and dummy:u events are implementation details and are expected to be empty.
 
-To get a full list of unique samples that are not sorted into groups, set the itrace option to
-generate 'instruction' samples. The period option is also taken into account, so set it to 1
-instruction unless you want to further downsample the already sampled SPE data:
+The instructions group contains the full list of unique samples that are not
+sorted into other groups. To generate only this group use --itrace=i1i.
 
-  perf report --itrace=i1i
+1i (1 instruction interval) signifies no further downsampling. Rather than an
+instruction interval, this generates a sample every n SPE samples. For example
+to generate the default set of events for every 100 SPE samples:
+
+  perf report --itrace==bxofmtMai100i
+
+Other period types, for example nanoseconds (ns) are not currently supported.
 
 Memory access details are also stored on the samples and this can be viewed with:
 

-- 
2.34.1