From 49b8e2beceda79ae25938faf68fad0ad62534852 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Sat, 3 Nov 2018 00:06:23 +0100 Subject: 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 Acked-by: Jiri Olsa Tested-by: Arnaldo Carvalho de Melo Cc: Alexander Shishkin Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20181102230624.20064-1-linux@rasmusvillemoes.dk Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-c2c.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tools/perf/builtin-c2c.c') diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c index d340d2e42776..f2863496dede 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"; -- cgit v1.2.3