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Re: How efficient is mounting /usr ro?

In article <[🔎] 200311261156.49129.russell@coker.com.au> you wrote:
> On Wed, 26 Nov 2003 07:45, Chema <chema.news.gmane@zarco.cjb.net> wrote:
>> RC> Why would you get better performance?  If you mount noatime then
>> RC> there's no writes to a file system that is accessed in a read-only
>> RC> fashion and there should not be any performance issue.
>> Hum, ¿are you talking only about ext3?  'Couse I don't think the reading
> I am talking about any file system.  When only reading from a file system 
> there should not be any performance difference when comparing a RO mount vs a 
> NOATIME mount.  If there is a difference then it's a bug in the file system.

I guess the thread was about non-journalling filesystems beeing faster, and
less of a risk if used ro.

> Incidentally if you want significantly better performance for such things then 
> you want to run 2.6.0 or a Red Hat kernel so you get directory hashing on 
> ext3.  It appears from a casual code inspection that 2.6.0-test10 does not 
> support directory hashing for ext2.  So in 2.6.0-test10 ext3 should 
> significantly outperform ext2 when there are large numbers of files in a 
> directory.  I'll have to do some benchmarks on this.

Yes, thats pretty interesting.

> The difference it makes is that reading from the disk will never cause disk 
> writes.  If you access large numbers of files or if you have IO hardware that 
> has a bottleneck of write bandwidth (EG a typical mail server) then NOATIME 
> makes a significant difference.

News Servers are even worth. And full-filesystem scans and some backup tools
make the a-time less usefull anyway.

eckes privat - http://www.eckes.org/
Project Freefire - http://www.freefire.org/

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