mirror of https://gitee.com/openkylin/linux.git
e369517ce5
Current collapse stage has a scalability problem which can be reproduced
easily with a parallel kernel build.
This is because it needs to traverse every children of callchains
linearly during the collapse/merge stage.
Converting it to a 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 <torvalds@linux-foundation.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1381468543-25334-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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