diff options
| author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2018-11-03 00:06:23 +0100 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2019-01-21 15:15:57 -0300 |
| commit | 49b8e2beceda79ae25938faf68fad0ad62534852 (patch) | |
| tree | c3420d22480616537313a38cc4de5a406436a535 /tools/perf/builtin-report.c | |
| parent | ad07c8ceb6631a83b62d405a61448bba92adac68 (diff) | |
perf tools: Replace automatic const char[] variables by statics
An automatic const char[] variable gets initialized at runtime, just
like any other automatic variable. For long strings, that uses a lot of
stack and wastes time building the string; e.g. for the "No %s
allocation events..." case one has:
444516: 48 b8 4e 6f 20 25 73 20 61 6c movabs $0x6c61207325206f4e,%rax # "No %s al"
...
444674: 48 89 45 80 mov %rax,-0x80(%rbp)
444678: 48 b8 6c 6f 63 61 74 69 6f 6e movabs $0x6e6f697461636f6c,%rax # "location"
444682: 48 89 45 88 mov %rax,-0x78(%rbp)
444686: 48 b8 20 65 76 65 6e 74 73 20 movabs $0x2073746e65766520,%rax # " events "
444690: 66 44 89 55 c4 mov %r10w,-0x3c(%rbp)
444695: 48 89 45 90 mov %rax,-0x70(%rbp)
444699: 48 b8 66 6f 75 6e 64 2e 20 20 movabs $0x20202e646e756f66,%rax
Make them all static so that the compiler just references objects in .rodata.
Committer testing:
Ok, using dwarves's codiff tool:
$ codiff --functions /tmp/perf.before ~/bin/perf
builtin-sched.c:
cmd_sched | -48
1 function changed, 48 bytes removed, diff: -48
builtin-report.c:
cmd_report | -32
1 function changed, 32 bytes removed, diff: -32
builtin-kmem.c:
cmd_kmem | -64
build_alloc_func_list | -50
2 functions changed, 114 bytes removed, diff: -114
builtin-c2c.c:
perf_c2c__report | -390
1 function changed, 390 bytes removed, diff: -390
ui/browsers/header.c:
tui__header_window | -104
1 function changed, 104 bytes removed, diff: -104
/home/acme/bin/perf:
9 functions changed, 688 bytes removed, diff: -688
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20181102230624.20064-1-linux@rasmusvillemoes.dk
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/builtin-report.c')
| -rw-r--r-- | tools/perf/builtin-report.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c index 4958095be4fc..794a0de5ac1d 100644 --- a/tools/perf/builtin-report.c +++ b/tools/perf/builtin-report.c @@ -956,9 +956,9 @@ int cmd_report(int argc, const char **argv) int branch_mode = -1; bool branch_call_mode = false; #define CALLCHAIN_DEFAULT_OPT "graph,0.5,caller,function,percent" - const char report_callchain_help[] = "Display call graph (stack chain/backtrace):\n\n" - CALLCHAIN_REPORT_HELP - "\n\t\t\t\tDefault: " CALLCHAIN_DEFAULT_OPT; + static const char report_callchain_help[] = "Display call graph (stack chain/backtrace):\n\n" + CALLCHAIN_REPORT_HELP + "\n\t\t\t\tDefault: " CALLCHAIN_DEFAULT_OPT; char callchain_default_opt[] = CALLCHAIN_DEFAULT_OPT; const char * const report_usage[] = { "perf report [<options>]", |