å 2016å3æ27æïäå11:20ïPeter Zijlstra <peterz@xxxxxxxxxxxxx> åéïFor some unknown reason, about
On Fri, Mar 25, 2016 at 10:14:36PM +0800, Wangnan (F) wrote:
x86_64-defconfigI think you enabled some unusual config options?
It has that indeed.You must enabled CONFIG_OPTIMIZE_INLINING. Now I get similar result:
After enabling CONFIG_OPTIMIZE_INLINING:Why is your variance so immense? And doesn't that render the
Test its performance by calling 'close(-1)' for 3000000 times and
use 'perf record -o /dev/null -e raw_syscalls:* test-ring-buffer' to
capture system calls:
BASE 800077.1 23448.13
RAWPERF.PRE 2465858.0 603473.70
RAWPERF.POST 2471925.0 609437.60
Considering the high stdvar, after applying this patch the performance
is not change.
10% of these results raises 2 times of normal
results. Say, "normal results" are about
2200000, but those "outliers" are about
4400000 (I can't access raw data now).
Variance becomes much smaller if I remove
I guess the outliers is caused by some type
of lock stepping? No clue about it.