Messages in this thread | | | From | Frederic Weisbecker <> | Subject | [GIT PULL] perf tools updates | Date | Thu, 30 Jun 2011 01:34:02 +0200 |
| |
Ingo,
Please pull the perf/core branch that can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git perf/core
It adds the inverted callchains support and let one use parent filtering with parent sorting at the same time, because it appears to me that inverted callchains sorted by filtered parents is pretty useful, and extendable to more cool things.
Anyway inverted callchains used with some different sorting combination in general can provide some interesting analysis flavours.
Having played with it a bit. It seems to me the callee point of view (traditional -g callchains) is better suited to find the precise zoomed-in places where cpu time is most spent. Spot contention places, etc...
OTOH, caller point of view (-G, inverted callchain), is for zoomed out observation, of course. It's more suited for global profiling. To get a big overview of where the hot bulk of a program is executing for example.
Examples:
- look at the hottest tree of call of a program.
./perf report -G -s pid --stdio
5.73% perf:11933 | --- __libc_start_main | |--99.18%-- main | run_builtin | cmd_bench | | | |--89.68%-- bench_sched_messaging | | | | | |--96.11%-- create_worker | | | | | | | |--95.10%-- __libc_fork | | | | | | | | | |--93.99%-- stub_clone | | | | | sys_clone | | | | | do_fork | | | | | | | | | | | |--99.09%-- copy_process | | | | | | | | | | | | | |--91.62%-- dup_mm
- look at where kernel threads spend their time
perf report -G -p kernel_thread -s parent --stdio # Overhead Parent symbol # ........ ............. # 0.07% kernel_thread_helper | --- kernel_thread_helper kthread | |--50.00%-- kjournald2 | jbd2_journal_commit_transaction | journal_submit_commit_record | submit_bh | submit_bio | generic_make_request | __make_request | __blk_run_queue | scsi_request_fn | scsi_dispatch_cmd | ata_scsi_queuecmd | ata_scsi_translate | ata_qc_issue | ata_bmdma_qc_issue | ata_sff_qc_issue | ata_sff_tf_load | ata_sff_check_status | ioread8 | --50.00%-- rcu_kthread rcu_process_callbacks delayed_put_task_struct __put_task_struct free_task free_thread_info free_thread_xstate kmem_cache_free __slab_free add_partial _raw_spin_lock lock_acquire etc...
We could extend that by applying some cut in the callchains. For example stop a callchain on a given dso and you can profile which exported function is most called in it.
Anyway, this has some nice potential.
Thanks, Frederic ---
Frederic Weisbecker (5): perf tools: Make sort operations static perf tools: Remove sort print helpers declarations perf tools: Don't display ignored entries on stdio ui perf tools: Allow sort dimensions to be registered more than once perf tools: Only display parent field if explictly sorted
Sam Liao (1): perf tools: Add inverted call graph report support.
tools/perf/Documentation/perf-report.txt | 15 ++- tools/perf/builtin-report.c | 42 +++++- tools/perf/util/callchain.h | 6 + tools/perf/util/hist.c | 6 +- tools/perf/util/session.c | 7 +- tools/perf/util/sort.c | 223 ++++++++++++++---------------- tools/perf/util/sort.h | 14 -- 7 files changed, 169 insertions(+), 144 deletions(-)
| |