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Commit 4cb93446 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

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 <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-yjqsd30nnkogvj5oyx9ghir9@git.kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c5dfd78e

tools/perf/Documentation/perf-report.txt

+1 −1
Original line number Diff line number Diff line
@@ -248,7 +248,7 @@ OPTIONS 
	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.



-G::

--inverted::

tools/perf/Documentation/perf-script.txt

+1 −1
Original line number Diff line number Diff line
@@ -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.



--ns::

	Use 9 decimal places when displaying time (i.e. show the nanoseconds)

tools/perf/Documentation/perf-top.txt

+1 −1
Original line number Diff line number Diff line
@@ -177,7 +177,7 @@ Default is to monitor all CPUS. 
	between information loss and faster processing especially for

	workloads that can have a very long callchain stack.



	Default: 127

	Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.



--ignore-callees=<regex>::

        Ignore callees of the function(s) matching the given regex.

tools/perf/Documentation/perf-trace.txt

+1 −1
Original line number Diff line number Diff line
@@ -143,7 +143,7 @@ the thread executes on the designated CPUs. Default is to monitor all CPUs. 
        Implies '--call-graph dwarf' when --call-graph not present on the

        command line, on systems where DWARF unwinding was built in.



        Default: 127

        Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.



--min-stack::

        Set the stack depth limit when parsing the callchain, anything

tools/perf/builtin-report.c

+2 −2
Original line number Diff line number Diff line
@@ -691,7 +691,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused) 
			.ordered_events	 = true,

			.ordering_requires_timestamps = true,

		},

		.max_stack		 = PERF_MAX_STACK_DEPTH,

		.max_stack		 = sysctl_perf_event_max_stack,

		.pretty_printing_style	 = "normal",

		.socket_filter		 = -1,

	};
@@ -744,7 +744,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused) 
	OPT_INTEGER(0, "max-stack", &report.max_stack,

		    "Set the maximum stack depth when parsing the callchain, "

		    "anything beyond the specified depth will be ignored. "

		    "Default: " __stringify(PERF_MAX_STACK_DEPTH)),

		    "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),

	OPT_BOOLEAN('G', "inverted", &report.inverted_callchain,

		    "alias for inverted call graph"),

	OPT_CALLBACK(0, "ignore-callees", NULL, "regex",