Bad file access on the rise

Steve Grubb sgrubb at redhat.com
Sat Jun 8 14:29:41 UTC 2013


On Saturday, June 08, 2013 10:13:45 AM Doug Ledford wrote:
> 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.

I chalk that up to the audit system.  The audit system tries real hard to stay 
out of the way since the vast majority of syscalls are not interesting. But if 
you trigger an event, it has to get recorded in gory detail and that takes 
time. (The first run did trigger 5000 audit events, the others didn't.) This is 
another reason (but not the main reason) we need to try to avoid triggering 
events in a normally operating machine.

-Steve


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