Re: [PATCH] HOWTO: add example of how to extract coverage files for autoFDO

On 16 December 2016 at 16:21, Sebastian Pop s.pop@samsung.com wrote:

Document all the steps to perform feedback directed optimization based on traces recorded by CoreSight ETM.

---

HOWTO.md | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+)

diff --git a/HOWTO.md b/HOWTO.md index 239a2cd..d96858e 100644 --- a/HOWTO.md +++ b/HOWTO.md @@ -518,6 +518,32 @@ will add the --dump option to the end of the command line and run ${PERF_EXEC_PATH}/perf report --stdio --dump

+Generating coverage files for Feedback Directed Optimization: AutoFDO +---------------------------------------------------------------------

+Below is an example of using ARM ETM for autoFDO. It requires autofdo +(https://github.com/google/autofdo) and gcc version 5. The bubble +sort example is from the AutoFDO tutorial (https://gcc.gnu.org/wiki/AutoFDO/Tutorial).

•    $ gcc-5 -O3 sort.c -o sort_optimized
  

•    $ taskset -c 2 ./sort_optimized
  

•    Bubble sorting array of 30000 elements
  

•    5910 ms
  

•    $ perf record -e cs_etm/@20070000.etr/u --per-thread taskset -c 2 ./sort
  

•    Bubble sorting array of 30000 elements
  

•    12543 ms
  

•    [ perf record: Woken up 35 times to write data ]
  

•    [ perf record: Captured and wrote 69.640 MB perf.data ]
  

•    $ perf inject -i perf.data -o inj.data --itrace=il64 --strip
  

•    $ create_gcov --binary=./sort --profile=inj.data --gcov=sort.gcov -gcov_version=1
  

•    $ gcc-5 -O3 -fauto-profile=sort.gcov sort.c -o sort_autofdo
  

•    $ taskset -c 2 ./sort_autofdo
  

•    Bubble sorting array of 30000 elements
  

•    5806 ms
  

The Linaro CoreSight Team

• Mike Leach

-- 2.6.3

Mike,

I have applied (and pushed) the autoFDO support patch to the perf-opencsd-4.10-rc2 branch. Please consider applying this patch to the master branch.

Thanks, Mathieu