Disabling atime

[Robert Nichols]

Rahul Sundaram wrote:
> Ralf Corsepius wrote:
>>> whether they want it or not now, they will learn when they need to.
>> Provide the results of the tests you exercised yourself. So far you
>> haven't. 
> 
> I gave you a reference. If you want more data, do the tests yourself.

OK, I ran my own test doing an rpmbuild of a custom kernel.  My
%_topdir and %_tmppath point to a filesystem that is normally
mounted noatime (it's primarily used as a news spool and work
area for backups), and my /usr is normally mounted read-only.
I tried several combinations and found no meaningful difference.

Build tree mounted noatime, /usr mounted read-only:
real    32m28.765s
user    43m11.627s
sys     4m36.532s

Build tree mounted atime, /usr mounted read-only:
real    32m39.343s
user    42m55.705s
sys     4m41.920s

Build tree mounted atime, /usr mounted rw,atime:
real    32m26.383s
user    43m1.042s
sys     4m42.099s

Repeating with build tree noatime, /usr read-only:
real    32m13.625s
user    42m59.867s
sys     4m39.544s

The tiny differences are totally masked by differences in the
amount of time GPG took for key generation.  The builds were
done on a 3.0 GHz Pentium 4 with Hyperthreading enabled and
1 GB of RAM.  The system was essentially idle except for the
builds.

As for enabling atime when I find I want it, that would likely
be when I want to see what files haven't been used in the last
6 months and I realize I should have enabled atime 6 months
ago.  Oops, too late now.

-- 
Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.