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    SubjectRe: [PATCH 0/4] perf tools: New comm infrastructure
    Em Tue, Sep 17, 2013 at 02:54:22PM +0900, Namhyung Kim escreveu:
    > Hi Ingo,
    >
    > On Sat, 14 Sep 2013 08:11:49 +0200, Ingo Molnar wrote:
    > > * Frederic Weisbecker <fweisbec@gmail.com> wrote:
    > >> My patches and Namhyung's should improve the comm situation a lot but we
    > >> can't do much miracle. The only way would be perhaps to be able to limit
    > >> the deepness of the callchain branches.
    > >>
    > >> Now may be we can find other big contention point in perf. It's possible
    > >> we also have some endless loop somewhere.
    > >
    > > Well, it was the 100,000+ step linear list walk that was causing 90% of
    > > the slowness here. Namhyung's patch should dramatically improve that. I
    > > guess time for someone to post a combined tree so that it can be tested
    > > all together?
    >
    > I pushed combined tree to 'perf/callchain-v2' branch in my tree
    >
    > git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git

    But you did it for some old tree, as I tried running it now and since my
    big perf.data file has PERF_RECORD_MMAP2 records, I can't try it with
    your branch, working on cherry picking those changesets, since a plain
    rebase didn't work.

    - Arnaldo

    >
    > Please note that I also pushed other versions (v[1-3]). The v1 is my
    > previous rbtree conversion patch, v2 adds Frederic's new comm
    > infrastructure series on top and v3 adds my revised patch to refer
    > current comm [1] on top of v2.
    >
    > I did my own test again among them. Test data is 400MB perf.data file
    > created by parallel kernel build.
    >
    > $ ls -lh perf.data.big
    > -rw-------. 1 namhyung namhyung 400M Sep 9 10:21 perf.data.big
    >
    > For more precise result, I changed cpufreq governor to 'performance'
    >
    > # echo performance > /sys/devices/system/cpu/cpu3/cpufreq/scaling_governor
    >
    > and run perf report on the cpu.
    >
    > $ taskset -c 3 time -p perf --no-pager report --stdio -i perf.data.big > /dev/null
    >
    > I ran it multiple times for each case and the results did not vary much.
    >
    > baseline v1 v2 v3
    > ----------------------------------------------------------
    > real 380.17 12.63 10.02 9.03
    > user 378.86 11.95 9.66 8.69
    > sys 0.70 0.65 0.33 0.34
    >
    >
    > I also tried to cache latest result and reuse it when adding a callchain
    > (in callchain_append() function) but it only hits ~5% and did not help
    > the performance.
    >
    > Thanks,
    > Namhyung
    >
    >
    > [1] https://lkml.org/lkml/2013/9/16/565


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