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Re: Disabling atime



Dr. Diesel wrote:
On 8/9/07, Rahul Sundaram <sundaram fedoraproject org> wrote:
Hi

http://kerneltrap.org/node/14148

Looks like we get a good performance boost and only tmpwatch and mutt
with mbox seems to be affected. A simple patch to tmpwatch has been
posted on the same thread.

Thoughts on disabling it?

Rahul

I have often thought an entire release (or every ~3-4) should consist
of nothing but bug fixes and code optimization.  Even at Ingo's 2.3%
it is worth a healthy discussion, which has already happened!  If much
faster machines could see 5-10% that would be a major improvement IMO.

I say lets try it!  How hard would it be to test?  ext3 is the biggest
issue, but there is a work-a-round?

I'm not sure anyone has mentioned what are probably the biggest uses of atime: (1) a debugging step to see if a file is actually being read by some process. For example you edit some config file, start the service and the change you expect didn't happen. If atime didn't change, the file wasn't read, perhaps due to some other directive passed earlier. Likewise with executables that you think should be run, or libraries that should be used. (2) as an indication that files have never been used and can probably be deleted. Since most backup operations act as a read, this tends to not be very useful.

Personally I'd trade these for better performance but I wouldn't want the change to be a surprise.

--
  Les Mikesell
   lesmikesell gmail com



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