On Fri, 2013-10-18 at 10:38 -0400, Waiman Long wrote:
> 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: Waiman Long <waiman.l...@hp.com>
Tested-by: Davidlohr Bueso <davidl...@hp.com>
> ---
> tools/perf/Documentation/perf-top.txt | 8 ++++++++
> tools/perf/builtin-top.c | 8 ++++++--
> tools/perf/util/top.h | 1 +
> 3 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-top.txt
> b/tools/perf/Documentation/perf-top.txt
> index 58d6598..3fd911c 100644
> --- a/tools/perf/Documentation/perf-top.txt
> +++ b/tools/perf/Documentation/perf-top.txt
> @@ -155,6 +155,14 @@ 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
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index 2725aca..14902b0 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -772,7 +772,7 @@ 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;
> }
> @@ -1052,10 +1052,11 @@ int cmd_top(int argc, const char **argv, const char
> *prefix __maybe_unused)
> .user_freq = UINT_MAX,
> .user_interval = ULLONG_MAX,
> .freq = 4000, /* 4 KHz */
> - .target = {
> + .target = {
> .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),
> diff --git a/tools/perf/util/top.h b/tools/perf/util/top.h
> index b554ffc..88cfeaf 100644
> --- a/tools/perf/util/top.h
> +++ b/tools/perf/util/top.h
> @@ -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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