Re: [PATCHSET 0/9] perf report: Improve srcline sort performance (v1)

[Ian Rogers]

On Thu, Dec 15, 2022 at 11:28 AM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> Hello,
>
> I noticed a performance problem in the srcline/srcfile processing during
> perf report when it's using an external addr2line process.  I guess it's
> also helpful even if it uses the libbfd to get the srcline info.
>
> Also note that it's mostly from large (static) binaries, but smaller
> binaries should also benefit from the fix if they have a lot of samples.
>
> The first 5 patches are general fixes and updates.  The latter 4 patches
> implemented the actual speed-up.
>
> Let's test it with the perf tools itself.  Build a static binary like below.
>
>   $ cd tools/perf
>   $ make NO_JVMTI=1 LDFLAGS=-static
>
> Then run the perf test workload.
>
>   $ ./perf record -- ./perf test -w noploop
>
> And run the perf report with srcline sort key like this.
>
>   $ ./perf report -n -s srcline --stdio
>   # To display the perf.data header info, please use --header/--header-only options.
>   #
>   #
>   # Total Lost Samples: 0
>   #
>   # Samples: 4K of event 'cycles:u'
>   # Event count (approx.): 3572938596
>   #
>   # Overhead       Samples  Source:Line
>   # ........  ............  ............
>   #
>       99.94%          4010  noploop.c:26
>        0.03%            14  ??:0
>        0.03%             1  perf.c:330
>        0.00%             1  wcscpy.o:0
>
> The problem is that it runs the addr2line when it processes each sample.
> But as you can see many samples can have same result.  IOW, if the samples
> have same address, we don't need to run the addr2line each time.
>
> So I changed the sort_key->cmp() to compare the addresses only and moved
> the addr2line from sort_key->collapse() so that they can be run after
> merging the samples with the same address.
>
> With the change, I can get a huge speed-up in processing srcline info
> while they generate the same output.
>
> Before:
>
>   $ ./perf stat -- ./perf report -s srcline > /dev/null
>
>    Performance counter stats for './perf report -s srcline':
>
>            15,397.13 msec task-clock:u                     #    0.993 CPUs utilized
>                    0      context-switches:u               #    0.000 /sec
>                    0      cpu-migrations:u                 #    0.000 /sec
>                3,810      page-faults:u                    #  247.449 /sec
>       54,516,351,820      cycles:u                         #    3.541 GHz
>       31,494,118,293      instructions:u                   #    0.58  insn per cycle
>        8,577,271,187      branches:u                       #  557.069 M/sec
>        1,216,165,520      branch-misses:u                  #   14.18% of all branches
>
>         15.505066606 seconds time elapsed
>
>         15.094122000 seconds user
>          0.396962000 seconds sys
>
> After:
>
>   $ ./perf stat -- ./perf report -s srcline > /dev/null
>
>    Performance counter stats for './perf report -s srcline':
>
>               105.66 msec task-clock:u                     #    0.994 CPUs utilized
>                    0      context-switches:u               #    0.000 /sec
>                    0      cpu-migrations:u                 #    0.000 /sec
>                3,275      page-faults:u                    #   30.995 K/sec
>          185,063,407      cycles:u                         #    1.751 GHz
>          142,470,215      instructions:u                   #    0.77  insn per cycle
>           34,584,038      branches:u                       #  327.311 M/sec
>            3,226,005      branch-misses:u                  #    9.33% of all branches
>
>          0.106270464 seconds time elapsed
>
>          0.074254000 seconds user
>          0.032871000 seconds sys
>
> The code is available at 'perf/srcline-v1' branch in
>
>   git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
>
> Thanks,
> Namhyung
>
>
> Namhyung Kim (9):
>   perf srcline: Do not return NULL for srcline
>   perf report: Ignore SIGPIPE for srcline
>   perf symbol: Add filename__has_section()
>   perf srcline: Skip srcline if .debug_line is missing
>   perf srcline: Conditionally suppress addr2line warnings
>   perf hist: Add perf_hpp_fmt->init() callback
>   perf hist: Improve srcline sort key performance
>   perf hist: Improve srcfile sort key performance
>   perf hist: Improve srcline_{from,to} sort key performance

Nice 145x performance win!

Series: Acked-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

>  tools/perf/builtin-report.c      |   1 +
>  tools/perf/util/hist.c           |  10 +--
>  tools/perf/util/hist.h           |   1 +
>  tools/perf/util/sort.c           | 129 ++++++++++++++++++++++++++++---
>  tools/perf/util/sort.h           |   1 +
>  tools/perf/util/srcline.c        |  20 +++--
>  tools/perf/util/symbol-elf.c     |  28 +++++++
>  tools/perf/util/symbol-minimal.c |   5 ++
>  tools/perf/util/symbol.h         |   1 +
>  9 files changed, 176 insertions(+), 20 deletions(-)
>
>
> base-commit: 818448e9cf92e5c6b3c10320372eefcbe4174e4f
> --
> 2.39.0.314.g84b9a713c41-goog
>