My orginal qustion:
>Is there any difference in performance when using link to directory on
>different disk or using the same directory as mounted disk?
Thanks to
Kurt Carlson <sxkac_at_java.sois.alaska.edu>
Anthony Talltree <aad_at_nwnet.net>
alan_at_nabeth.cxo.dec.com (Alan Rollow).
who replayed,
As I tought the differences in performance are minimal, and we can
ignore them :
> Not enough to worry about. Anything used frequently will get cached any.
> If you do nothing more than open
> and close files, you might be able to measure the small amount of
> time it takes to traverse the symbolic link compared to traverseing
>the mounted file system. Still, if all you're doing is opening and
>close files, the overhead of updating the access time is likely to
>dominate the time. Any application that is more substantial would
>probably make the difference harder to measure.
>So, strictly speaking, I believe the code path to used to traverse
>the link is longer than one to traverse the mounted directory. If
>nothing else, once the link is resolved the working of traversing
>the directory has to be done anyway. This other file system must
>be mounted somewhere to be accessible. That might cause enough CPU
>cycles to make it measureable under the right load. More likely
>compared to the other work, it won't be measureable, except perhaps
>by a cycle counter.
>When in doubt benchmark. Construct a test resembling the work load
>you're going to put the configuration under and measure the time it
>takes either way. If one is statistically faster than the other,
>and the linking is only difference, then you'll have a good idea
>which is faster.
>Not really, there is an extra directory processed but that's trivial.
>The only real difference would be in the performance of the disks
>themselves... if you had a hot file on one disk that was hurting
>the entire disk (say /usr), moving the file and keeping standard
>access via a link is a good idea.
--
regards,
All above opinions are personal, unless stated otherwise.
---------------------------------------------------------------
Ran Zahor - UNIX System Manager | Email : ran_at_wiztec.co.il
Wiztec Solutions Ltd. | Phone : (972)-9-9526557
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Received on Mon Apr 07 1997 - 13:55:23 NZST