path: root/tools/perf/Documentation/perf-script.txt
diff options
authorArnaldo Carvalho de Melo <>2016-04-27 10:16:24 -0300
committerArnaldo Carvalho de Melo <>2016-04-27 10:29:07 -0300
commit4cb93446c587d56e2a54f4f83113daba2c0b6dee (patch)
treea251b1d510831dc071eadbbbe3e38a85fe643365 /tools/perf/Documentation/perf-script.txt
parentc5dfd78eb79851e278b7973031b9ca363da87a7e (diff)
perf tools: Set the maximum allowed stack from /proc/sys/kernel/perf_event_max_stack
There is an upper limit to what tooling considers a valid callchain, and it was tied to the hardcoded value in the kernel, PERF_MAX_STACK_DEPTH (127), now that this can be tuned via a sysctl, make it read it and use that as the upper limit, falling back to PERF_MAX_STACK_DEPTH for kernels where this sysctl isn't present. Cc: Adrian Hunter <> Cc: Brendan Gregg <> Cc: David Ahern <> Cc: Frederic Weisbecker <> Cc: Jiri Olsa <> Cc: Milian Wolff <> Cc: Namhyung Kim <> Cc: Wang Nan <> Link: Signed-off-by: Arnaldo Carvalho de Melo <>
Diffstat (limited to 'tools/perf/Documentation/perf-script.txt')
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index 4fc44c75263f..a856a1095893 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -267,7 +267,7 @@ include::itrace.txt[]
Note that when using the --itrace option the synthesized callchain size
will override this value if the synthesized callchain size is bigger.
- Default: 127
+ Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.
Use 9 decimal places when displaying time (i.e. show the nanoseconds)