On Wed, 2 Oct 2013 12:18:28 +0200, Frederic Weisbecker wrote: > On Thu, Sep 26, 2013 at 05:58:03PM +0900, Namhyung Kim wrote: >> From: Namhyung Kim <namhyung....@lge.com> >> >> Current collapse stage has a scalability problem which can be >> reproduced easily with parallel kernel build. This is because it >> needs to traverse every children of callchain linearly during the >> collapse/merge stage. Convert it to rbtree reduced the overhead >> significantly. >> >> On my 400MB perf.data file which recorded with make -j32 kernel build: >> >> $ time perf --no-pager report --stdio > /dev/null >> >> before: >> real 6m22.073s >> user 6m18.683s >> sys 0m0.706s >> >> after: >> real 0m20.780s >> user 0m19.962s >> sys 0m0.689s >> >> During the perf report the overhead on append_chain_children went down >> from 96.69% to 18.16%: >> >> - 18.16% perf perf [.] append_chain_children >> - append_chain_children >> - 77.48% append_chain_children >> + 69.79% merge_chain_branch >> - 22.96% append_chain_children >> + 67.44% merge_chain_branch >> + 30.15% append_chain_children >> + 2.41% callchain_append >> + 7.25% callchain_append >> + 12.26% callchain_append >> + 10.22% merge_chain_branch >> + 11.58% perf perf [.] dso__find_symbol >> + 8.02% perf perf [.] sort__comm_cmp >> + 5.48% perf libc-2.17.so [.] malloc_consolidate >> >> Reported-by: Linus Torvalds <torva...@linux-foundation.org> >> Cc: Jiri Olsa <jo...@redhat.com> >> Cc: Frederic Weisbecker <fweis...@gmail.com> >> Link: http://lkml.kernel.org/n/tip-d9tcfow6stbrp4btvgs51...@git.kernel.org >> Signed-off-by: Namhyung Kim <namhy...@kernel.org> > > Have you tested this patchset when collapsing is not used? > There are fair chances that this patchset does not only improve collapsing > but also callchain insertion in general. So it's probably a win in any case. > But > still it would be nice to make sure that it's the case because we are getting > rid of collapsing anyway. > > The test that could tell us about that is to run "perf report -s sym" and > compare the > time it takes to complete before and after this patch, because "-s sym" > shouldn't > involve collapses. > > Sorting by anything that is not comm should do the trick in fact.
Yes, I have similar result when collapsing is not used. Actually when I ran "perf report -s sym", the performance improves higher since it'd insert more callchains in a hist entry. Thanks, Namhyung -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
