[PATCH] perf: replace automatic const char[] variables by statics
From: Rasmus Villemoes
Date: Fri Nov 02 2018 - 19:13:58 EST
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.
Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
---
tools/perf/builtin-c2c.c | 4 ++--
tools/perf/builtin-kmem.c | 4 ++--
tools/perf/builtin-report.c | 6 +++---
tools/perf/builtin-sched.c | 2 +-
tools/perf/ui/browsers/header.c | 2 +-
tools/perf/ui/browsers/hists.c | 4 ++--
6 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index f3aa9d02a5ab..ab6a89e5393c 100644
--- a/tools/perf/builtin-c2c.c
+++ b/tools/perf/builtin-c2c.c
@@ -2343,7 +2343,7 @@ static int perf_c2c__browse_cacheline(struct hist_entry *he)
struct c2c_cacheline_browser *cl_browser;
struct hist_browser *browser;
int key = -1;
- const char help[] =
+ static const char help[] =
" ENTER Toggle callchains (if present) \n"
" n Toggle Node details info \n"
" s Toggle full length of symbol and source line columns \n"
@@ -2424,7 +2424,7 @@ static int perf_c2c__hists_browse(struct hists *hists)
{
struct hist_browser *browser;
int key = -1;
- const char help[] =
+ static const char help[] =
" d Display cacheline details \n"
" ENTER Toggle callchains (if present) \n"
" q Quit \n";
diff --git a/tools/perf/builtin-kmem.c b/tools/perf/builtin-kmem.c
index b63bca4b0c2a..088705c167bf 100644
--- a/tools/perf/builtin-kmem.c
+++ b/tools/perf/builtin-kmem.c
@@ -334,7 +334,7 @@ static int build_alloc_func_list(void)
struct alloc_func *func;
struct machine *machine = &kmem_session->machines.host;
regex_t alloc_func_regex;
- const char pattern[] = "^_?_?(alloc|get_free|get_zeroed)_pages?";
+ static const char pattern[] = "^_?_?(alloc|get_free|get_zeroed)_pages?";
ret = regcomp(&alloc_func_regex, pattern, REG_EXTENDED);
if (ret) {
@@ -1924,7 +1924,7 @@ int cmd_kmem(int argc, const char **argv)
NULL
};
struct perf_session *session;
- const char errmsg[] = "No %s allocation events found. Have you run 'perf kmem record --%s'?\n";
+ static const char errmsg[] = "No %s allocation events found. Have you run 'perf kmem record --%s'?\n";
int ret = perf_config(kmem_config, NULL);
if (ret)
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 257c9c18cb7e..ff615c624784 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -955,9 +955,9 @@ 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>]",
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index cbf39dab19c1..2e0f0c65964a 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -3336,7 +3336,7 @@ static int __cmd_record(int argc, const char **argv)
int cmd_sched(int argc, const char **argv)
{
- const char default_sort_order[] = "avg, max, switch, runtime";
+ static const char default_sort_order[] = "avg, max, switch, runtime";
struct perf_sched sched = {
.tool = {
.sample = perf_sched__process_tracepoint_sample,
diff --git a/tools/perf/ui/browsers/header.c b/tools/perf/ui/browsers/header.c
index d75492189acb..5aeb663dd184 100644
--- a/tools/perf/ui/browsers/header.c
+++ b/tools/perf/ui/browsers/header.c
@@ -35,7 +35,7 @@ static int list_menu__run(struct ui_browser *menu)
{
int key;
unsigned long offset;
- const char help[] =
+ static const char help[] =
"h/?/F1 Show this window\n"
"UP/DOWN/PGUP\n"
"PGDN/SPACE\n"
diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index a96f62ca984a..eab9dc025b3a 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -2737,7 +2737,7 @@ 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"
@@ -2745,7 +2745,7 @@ 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"
--
2.19.1.6.gbde171bbf5