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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
parent53dbabfe50262eeebb56ce18789c3c885f15e6ac (diff)
downloadlinux-382619c07ff6491b33d54fccff7407336ddcb6d4.tar.bz2
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')
-rw-r--r--tools/perf/util/thread.c3
-rw-r--r--tools/perf/util/unwind-libunwind-local.c6
-rw-r--r--tools/perf/util/unwind-libunwind.c10
3 files changed, 12 insertions, 7 deletions
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 50678d318185..403045a2bbea 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -15,6 +15,7 @@
#include "map.h"
#include "symbol.h"
#include "unwind.h"
+#include "callchain.h"
#include <api/fs/fs.h>
@@ -327,7 +328,7 @@ static int thread__prepare_access(struct thread *thread)
{
int err = 0;
- if (symbol_conf.use_callchain)
+ if (dwarf_callchain_users)
err = __thread__prepare_access(thread);
return err;
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);
}
diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c
index 9778b3133b77..c0811977d7d5 100644
--- a/tools/perf/util/unwind-libunwind.c
+++ b/tools/perf/util/unwind-libunwind.c
@@ -5,6 +5,7 @@
#include "session.h"
#include "debug.h"
#include "env.h"
+#include "callchain.h"
struct unwind_libunwind_ops __weak *local_unwind_libunwind_ops;
struct unwind_libunwind_ops __weak *x86_32_unwind_libunwind_ops;
@@ -24,6 +25,9 @@ int unwind__prepare_access(struct thread *thread, struct map *map,
struct unwind_libunwind_ops *ops = local_unwind_libunwind_ops;
int err;
+ if (!dwarf_callchain_users)
+ return 0;
+
if (thread->addr_space) {
pr_debug("unwind: thread map already set, dso=%s\n",
map->dso->name);
@@ -65,12 +69,18 @@ out_register:
void unwind__flush_access(struct thread *thread)
{
+ if (!dwarf_callchain_users)
+ return;
+
if (thread->unwind_libunwind_ops)
thread->unwind_libunwind_ops->flush_access(thread);
}
void unwind__finish_access(struct thread *thread)
{
+ if (!dwarf_callchain_users)
+ return;
+
if (thread->unwind_libunwind_ops)
thread->unwind_libunwind_ops->finish_access(thread);
}