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>
diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index ffac1d5..b32f505 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -2748,7 +2748,7 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
"S Zoom into current Processor Socket\n" \
/* help messages are sorted by lexical order of the hotkey */
- const char report_help[] = HIST_BROWSER_HELP_COMMON
+ static const char report_help[] = HIST_BROWSER_HELP_COMMON
"i Show header information\n"
"P Print histograms to perf.hist.N\n"
"r Run available scripts\n"
@@ -2756,7 +2756,7 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
"t Zoom into current Thread\n"
"V Verbose (DSO names in callchains, etc)\n"
"/ Filter symbol by name";
- const char top_help[] = HIST_BROWSER_HELP_COMMON
+ static const char top_help[] = HIST_BROWSER_HELP_COMMON
"P Print histograms to perf.hist.N\n"
"t Zoom into current Thread\n"
"V Verbose (DSO names in callchains, etc)\n"
