From 846e1939801a0893ea71a6a56d8dbe2bf46682d1 Mon Sep 17 00:00:00 2001 From: Changbin Du Date: Sat, 8 Aug 2020 10:31:27 +0800 Subject: [PATCH] perf ftrace: Add option '-m/--buffer-size' to set per-cpu buffer size This adds an option '-m/--buffer-size' to allow us set the size of per-cpu tracing buffer. Committer testing: Before running with this option: # find /sys/kernel/tracing/ -name buffer_size_kb | xargs cat 1408 1408 1408 1408 1408 1408 1408 1408 1408 # Then, run: # perf ftrace -m 2048K | head -10 2) | mutex_unlock() { 2) ==========> | 2) | smp_irq_work_interrupt() { 2) | irq_enter() { 2) 0.121 us | rcu_irq_enter(); 2) 0.128 us | irqtime_account_irq(); 2) 0.719 us | } 2) | __wake_up() { 2) | __wake_up_common_lock() { 2) 0.105 us | _raw_spin_lock_irqsave(); # Now look at those tracefs knobs: # find /sys/kernel/tracing/ -name buffer_size_kb | xargs cat 2048 2048 2048 2048 2048 2048 2048 2048 2048 # This should be similar to the -m option in the other perf tools, such as 'perf record', 'perf trace', etc. Signed-off-by: Changbin Du Acked-by: Namhyung Kim Tested-by: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Peter Zijlstra Cc: Steven Rostedt (VMware) Link: http://lore.kernel.org/lkml/20200808023141.14227-5-changbin.du@gmail.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-ftrace.txt | 5 +++ tools/perf/builtin-ftrace.c | 55 ++++++++++++++++++++++++ 2 files changed, 60 insertions(+) diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt index 4f5628445a63..7a5d915f60b0 100644 --- a/tools/perf/Documentation/perf-ftrace.txt +++ b/tools/perf/Documentation/perf-ftrace.txt @@ -53,6 +53,11 @@ OPTIONS Ranges of CPUs are specified with -: 0-2. Default is to trace on all online CPUs. +-m:: +--buffer-size:: + Set the size of per-cpu tracing buffer, is expected to + be a number with appended unit character - B/K/M/G. + -T:: --trace-funcs=:: Select function tracer and set function filter on the given diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c index 4b3fcee5725a..a3a4f4be9dde 100644 --- a/tools/perf/builtin-ftrace.c +++ b/tools/perf/builtin-ftrace.c @@ -26,6 +26,7 @@ #include "thread_map.h" #include "util/cap.h" #include "util/config.h" +#include "util/units.h" #define DEFAULT_TRACER "function_graph" @@ -39,6 +40,7 @@ struct perf_ftrace { struct list_head graph_funcs; struct list_head nograph_funcs; int graph_depth; + unsigned long percpu_buffer_size; }; struct filter_entry { @@ -324,6 +326,21 @@ static int set_tracing_depth(struct perf_ftrace *ftrace) return 0; } +static int set_tracing_percpu_buffer_size(struct perf_ftrace *ftrace) +{ + int ret; + + if (ftrace->percpu_buffer_size == 0) + return 0; + + ret = write_tracing_file_int("buffer_size_kb", + ftrace->percpu_buffer_size / 1024); + if (ret < 0) + return ret; + + return 0; +} + static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) { char *trace_file; @@ -388,6 +405,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) goto out_reset; } + if (set_tracing_percpu_buffer_size(ftrace) < 0) { + pr_err("failed to set tracing per-cpu buffer size\n"); + goto out_reset; + } + if (write_tracing_file("current_tracer", ftrace->tracer) < 0) { pr_err("failed to set current_tracer to %s\n", ftrace->tracer); goto out_reset; @@ -506,6 +528,37 @@ static void delete_filter_func(struct list_head *head) } } +static int parse_buffer_size(const struct option *opt, + const char *str, int unset) +{ + unsigned long *s = (unsigned long *)opt->value; + static struct parse_tag tags_size[] = { + { .tag = 'B', .mult = 1 }, + { .tag = 'K', .mult = 1 << 10 }, + { .tag = 'M', .mult = 1 << 20 }, + { .tag = 'G', .mult = 1 << 30 }, + { .tag = 0 }, + }; + unsigned long val; + + if (unset) { + *s = 0; + return 0; + } + + val = parse_tag_value(str, tags_size); + if (val != (unsigned long) -1) { + if (val < 1024) { + pr_err("buffer size too small, must larger than 1KB."); + return -1; + } + *s = val; + return 0; + } + + return -1; +} + static void select_tracer(struct perf_ftrace *ftrace) { bool graph = !list_empty(&ftrace->graph_funcs) || @@ -560,6 +613,8 @@ int cmd_ftrace(int argc, const char **argv) "Set nograph filter on given functions", parse_filter_func), OPT_INTEGER('D', "graph-depth", &ftrace.graph_depth, "Max depth for function graph tracer"), + OPT_CALLBACK('m', "buffer-size", &ftrace.percpu_buffer_size, "size", + "size of per cpu buffer", parse_buffer_size), OPT_END() };