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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2018-11-03 00:06:23 +0100
committerArnaldo Carvalho de Melo <acme@redhat.com>2019-01-21 15:15:57 -0300
commit49b8e2beceda79ae25938faf68fad0ad62534852 (patch)
treec3420d22480616537313a38cc4de5a406436a535 /tools/perf/builtin-report.c
parentad07c8ceb6631a83b62d405a61448bba92adac68 (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.c6
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>]",