[Gluster-devel] ls again
Anand Avati
avati at zresearch.com
Mon Apr 7 14:08:47 UTC 2008
Reinis,
ls commands on modern GNU/Linux systems run xattr calls on each entry for
ACL purposes. This can turn out to be pretty expensive in terms of
performance. If you just run /bin/ls, or ls after 'unalias ls', you should
observe that the performance improves quite a bit, either because both
stat() and xattr calls were skipped, or because just stat() calls were
skipped.
avati
2008/4/7, Reinis Rozitis <roze at roze.lv>:
>
> Hello,
> there have been some threads in the past about 'ls' being slow on large
> file
> directories but my question is more regarding documentation:
>
> According to http://www.gluster.org/docs/index.php/GlusterFS_FAQ - "Just
> doing "ls" doesn't trigger stat call. It should be fast as this is called
> only on the namespace child."
>
> But actually on our system/setup (where namespace resides on seperate
> partition (c0d0) and the storage bricks are different pairs of disks
> (c1d0-c2d6) mounted together with unify) we see that after doing 'ls' a
> sequence starts which reads every storage brick (and not only namespace).
>
>
> In iostat it looks something like this (I hope the spacing won't break):
>
> avg-cpu: %user %nice %system %iowait %steal %idle
> 0.00 0.00 0.50 0.00 0.00 99.50
>
> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
> cciss/c0d0 0.00 0.00 0.00 0 0
> cciss/c1d0 0.00 0.00 0.00 0 0
> cciss/c1d1 0.00 0.00 0.00 0 0
> cciss/c1d2 0.00 0.00 0.00 0 0
> cciss/c1d3 189.00 3008.00 0.00 3008 0
> cciss/c1d4 0.00 0.00 0.00 0 0
> cciss/c1d5 0.00 0.00 0.00 0 0
> cciss/c1d6 0.00 0.00 0.00 0 0
> cciss/c1d7 0.00 0.00 0.00 0 0
> cciss/c1d8 0.00 0.00 0.00 0 0
> cciss/c1d9 0.00 0.00 0.00 0 0
> cciss/c2d0 0.00 0.00 0.00 0 0
> cciss/c2d1 0.00 0.00 0.00 0 0
> cciss/c2d2 0.00 0.00 0.00 0 0
> cciss/c2d3 0.00 0.00 0.00 0 0
> cciss/c2d4 0.00 0.00 0.00 0 0
> cciss/c2d5 0.00 0.00 0.00 0 0
> cciss/c2d6 0.00 0.00 0.00 0 0
>
>
> There is only one partition being read at time when it finishes it
> switches
> to the next. Sometimes the loop goes even 2 or 3 times before the
> directory/file listing is returned. So it takes pretty long after the
> mounted partition becomes responsive.
>
> I wonder is it supposed to be so or the 'ls' from OpenSuse "breaks" the
> whole thing (because it adds some commandline params on its own - full
> command looks like 'ls -N --color=tty -T 0 -1')
>
> wbr
> Reinis Rozitis
>
>
>
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>
--
If I traveled to the end of the rainbow
As Dame Fortune did intend,
Murphy would be there to tell me
The pot's at the other end.
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