From: Namhyung Kim Date: Tue, 14 May 2013 02:09:03 +0000 (+0900) Subject: perf report: Don't bother locking when adding hist entries X-Git-Tag: omap-for-v3.11/fixes-for-merge-window~62^2~26^2~44 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f3dd19817e5bbcae81e96571a3d42aa30a1581fb;p=pandora-kernel.git perf report: Don't bother locking when adding hist entries The 'perf report'command is single-threaded, so no need to grab a lock. Although the fast path of pthread_mutex_[un]lock() is very fast, there's a ~3% gain by eliminating it when we have huge sample data. $ perf record -a -F 100000 -o perf.data.bench -- perf bench sched all $ perf record -e cycles:upp -o perf.data.before -- \ > perf report -i perf.data.bench --stdio > /dev/null ... apply this patch ... $ perf record -e cycles:upp -o perf.data.after -- \ > perf report -i perf.data.bench --stdio > /dev/null $ perf diff perf.data.{before,after} | grep pthread +0.02% libpthread-2.15.so [.] _pthread_cleanup_push_defer +0.02% libpthread-2.15.so [.] _pthread_cleanup_pop_restore 0.05% -0.05% perf [.] pthread_mutex_unlock@plt 0.05% -0.05% perf [.] pthread_mutex_lock@plt 1.01% -1.01% libpthread-2.15.so [.] pthread_mutex_lock 1.68% -1.68% libpthread-2.15.so [.] __pthread_mutex_unlock_usercnt 0.05% -0.05% libpthread-2.15.so [.] pthread_mutex_unlock Signed-off-by: Namhyung Kim Acked-by: Jiri Olsa Cc: David Ahern Cc: Ingo Molnar Cc: Jiri Olsa Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Stephane Eranian Link: http://lkml.kernel.org/r/1368497347-9628-6-git-send-email-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- Reading git-diff-tree failed