Commit 5dbb6e81 authored by Waiman Long's avatar Waiman Long Committed by Arnaldo Carvalho de Melo
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perf top: Add --max-stack option to limit callchain stack scan 



When the callgraph function is enabled (-G), it may take a long time to
scan all the stack data and merge them accordingly.

This patch adds a new --max-stack option to perf-top to limit the depth
of callchain stack data to look at to reduce the time it takes for
perf-top to finish its processing. It reduces the amount of information
provided to the user in exchange for faster speed.

Signed-off-by: default avatarWaiman Long <Waiman.Long@hp.com>
Acked-by: default avatarDavid Ahern <dsahern@gmail.com>
Tested-by: default avatarDavidlohr Bueso <davidlohr@hp.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1382107129-2010-5-git-send-email-Waiman.Long@hp.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 91e95617

tools/perf/Documentation/perf-top.txt

+8 −0
Original line number Diff line number Diff line
@@ -158,6 +158,14 @@ Default is to monitor all CPUS. 


	Default: fractal,0.5,callee.



--max-stack::

	Set the stack depth limit when parsing the callchain, anything

	beyond the specified depth will be ignored. This is a trade-off

	between information loss and faster processing especially for

	workloads that can have a very long callchain stack.



	Default: 127



--ignore-callees=<regex>::

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

        This has the effect of collecting the callers of each such

tools/perf/builtin-top.c

+6 −2
Original line number Diff line number Diff line
@@ -771,7 +771,7 @@ static void perf_event__process_sample(struct perf_tool *tool, 
			err = machine__resolve_callchain(machine, evsel,

							 al.thread, sample,

							 &parent, &al,

							 PERF_MAX_STACK_DEPTH);

							 top->max_stack);

			if (err)

				return;

		}
@@ -1052,6 +1052,7 @@ int cmd_top(int argc, const char **argv, const char *prefix __maybe_unused) 
				.uses_mmap   = true,

			},

		},

		.max_stack	     = PERF_MAX_STACK_DEPTH,

		.sym_pcnt_filter     = 5,

	};

	struct perf_record_opts *opts = &top.record_opts;
@@ -1110,6 +1111,9 @@ int cmd_top(int argc, const char **argv, const char *prefix __maybe_unused) 
	OPT_CALLBACK_DEFAULT('G', "call-graph", &top.record_opts,

			     "mode[,dump_size]", record_callchain_help,

			     &parse_callchain_opt, "fp"),

	OPT_INTEGER(0, "max-stack", &top.max_stack,

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

		    "Default: " __stringify(PERF_MAX_STACK_DEPTH)),

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

		   "ignore callees of these functions in call graphs",

		   report_parse_ignore_callees_opt),

tools/perf/util/top.h

+1 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ struct perf_top { 
	u64		   exact_samples;

	u64		   guest_us_samples, guest_kernel_samples;

	int		   print_entries, count_filter, delay_secs;

	int		   max_stack;

	bool		   hide_kernel_symbols, hide_user_symbols, zero;

	bool		   use_tui, use_stdio;

	bool		   kptr_restrict_warned;

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