On 06/08/2013 10:10 AM, Steve Grubb wrote:
On Saturday, June 08, 2013 09:57:03 AM Doug Ledford wrote:
> Bad test. The first run took the hit for getting the file info into
> page cache, after that, everything was run from cache and you got the
> second result above and the results below. You have to make sure that
> from run to run the cache state of the file in question is identical.
Try it yourself. :-) I know what you are saying and run the test probably 8
times before posting results. I also have the audit rule loaded...so removing
it:
[sgrubb@x2 noatime]$ time ./test noatime
real 0m0.031s
user 0m0.006s
sys 0m0.024s
[sgrubb@x2 noatime]$ time ./test noatime
real 0m0.033s
user 0m0.002s
sys 0m0.032s
[sgrubb@x2 noatime]$ time ./test noatime
real 0m0.036s
user 0m0.002s
sys 0m0.031s
[sgrubb@x2 noatime]$ time ./test atime
real 0m0.023s
user 0m0.001s
sys 0m0.021s
[sgrubb@x2 noatime]$ time ./test atime
real 0m0.022s
user 0m0.003s
sys 0m0.019s
[sgrubb@x2 noatime]$ time ./test atime
real 0m0.023s
user 0m0.002s
sys 0m0.019s
Without the audit rules, it is faster. But again opening with noatime
attempted is measurably slower.
Yes, but none of these results show the .12s time that your first
noatime test run showed in your original post. If you are now saying
that atime is faster than noatime by about .005 to .010s, then these
results seem to show that. But your original post was from .019 to .12,
or a difference of .10+s. That was cache load time, not just the
syscall difference.