Em Sat, Nov 03, 2018 at 12:06:23AM +0100, Rasmus Villemoes escreveu: > 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. >
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 Thanks, applied. - Arnaldo
