perf_counter: minimize context time updates
Push the update_context_time() calls up the stack so that we get less
invokations and thereby a less noisy output:
before:
# ./perfstat -e 1:0 -e 1:1 -e 1:1 -e 1:1 -l ls > /dev/null
Performance counter stats for 'ls':
10.163691 cpu clock ticks (msecs) (scaled from 98.94%)
10.215360 task clock ticks (msecs) (scaled from 98.18%)
10.185549 task clock ticks (msecs) (scaled from 98.53%)
10.183581 task clock ticks (msecs) (scaled from 98.71%)
Wall-clock time elapsed: 11.912858 msecs
after:
# ./perfstat -e 1:0 -e 1:1 -e 1:1 -e 1:1 -l ls > /dev/null
Performance counter stats for 'ls':
9.316630 cpu clock ticks (msecs)
9.280789 task clock ticks (msecs)
9.280789 task clock ticks (msecs)
9.280789 task clock ticks (msecs)
Wall-clock time elapsed: 9.574872 msecs
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.618876874@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
1 file changed