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authorJiri Olsa <jolsa@kernel.org>2019-04-26 09:38:04 +0200
committerArnaldo Carvalho de Melo <acme@redhat.com>2019-05-15 16:36:46 -0300
commit382619c07ff6491b33d54fccff7407336ddcb6d4 (patch)
tree9ac1506d1c6afe0fec2b2b4c06eecf089ebf2456 /tools/perf/util/unwind-libunwind-local.c
parent53dbabfe50262eeebb56ce18789c3c885f15e6ac (diff)
perf tools: Speed up report for perf compiled with linwunwind
When compiled with libunwind, perf does some preparatory work when processing side-band events. This is not needed when report actually don't unwind dwarf callchains, so it's disabled with dwarf_callchain_users bool. However we could move that check to higher level and shield more unwanted code for normal report processing, giving us following speed up on kernel build profile: Before: $ perf record make -j40 ... $ ll ../../perf.data -rw-------. 1 jolsa jolsa 461783932 Apr 26 09:11 perf.data $ perf stat -e cycles:u,instructions:u perf report -i perf.data > out Performance counter stats for 'perf report -i perf.data': 78,669,920,155 cycles:u 99,076,431,951 instructions:u # 1.26 insn per cycle 55.382823668 seconds time elapsed 27.512341000 seconds user 27.712871000 seconds sys After: $ perf stat -e cycles:u,instructions:u perf report -i perf.data > out Performance counter stats for 'perf report -i perf.data': 59,626,798,904 cycles:u 88,583,575,849 instructions:u # 1.49 insn per cycle 21.296935559 seconds time elapsed 20.010191000 seconds user 1.202935000 seconds sys The speed is higher with profile having many side-band events, because these trigger libunwind preparatory code. This does not apply for perf compiled with libdw for dwarf unwind, only for build with libunwind. Signed-off-by: Jiri Olsa <jolsa@kernel.org> 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/20190426073804.17238-1-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/unwind-libunwind-local.c')
-rw-r--r--tools/perf/util/unwind-libunwind-local.c6
1 files changed, 0 insertions, 6 deletions
diff --git a/tools/perf/util/unwind-libunwind-local.c b/tools/perf/util/unwind-libunwind-local.c
index f3c666a84e4d..25e1406b1f8b 100644
--- a/tools/perf/util/unwind-libunwind-local.c
+++ b/tools/perf/util/unwind-libunwind-local.c
@@ -617,8 +617,6 @@ static unw_accessors_t accessors = {
static int _unwind__prepare_access(struct thread *thread)
{
- if (!dwarf_callchain_users)
- return 0;
thread->addr_space = unw_create_addr_space(&accessors, 0);
if (!thread->addr_space) {
pr_err("unwind: Can't create unwind address space.\n");
@@ -631,15 +629,11 @@ static int _unwind__prepare_access(struct thread *thread)
static void _unwind__flush_access(struct thread *thread)
{
- if (!dwarf_callchain_users)
- return;
unw_flush_cache(thread->addr_space, 0, 0);
}
static void _unwind__finish_access(struct thread *thread)
{
- if (!dwarf_callchain_users)
- return;
unw_destroy_addr_space(thread->addr_space);
}