diff options
author | Jiri Olsa <jolsa@kernel.org> | 2019-04-26 09:38:04 +0200 |
---|---|---|
committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2019-05-15 16:36:46 -0300 |
commit | 382619c07ff6491b33d54fccff7407336ddcb6d4 (patch) | |
tree | 9ac1506d1c6afe0fec2b2b4c06eecf089ebf2456 /tools/perf | |
parent | 53dbabfe50262eeebb56ce18789c3c885f15e6ac (diff) | |
download | linux-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.c | 3 | ||||
-rw-r--r-- | tools/perf/util/unwind-libunwind-local.c | 6 | ||||
-rw-r--r-- | tools/perf/util/unwind-libunwind.c | 10 |
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); } |