Re: Strange delete performance using XFS

Justin Piszcz
2007-04-04T13:57:26Z

[-- Attachment #1: Type: TEXT/PLAIN, Size: 2448 bytes --]

On Wed, 4 Apr 2007, Thomas Kaehn wrote:

> Hi Justin,
>
> On Wed, Apr 04, 2007 at 09:29:46AM -0400, Justin Piszcz wrote:
>>> Please see below for "time" output.
>>>
>>> | # time for i in `seq 1 100000`; do dd if=/dev/zero of=$i bs=1k count=20
>>>> /dev/null 2>&1; done
>>> |
>>> | real 6m6.814s
>>> | user 0m30.290s
>>> | sys 2m42.562s
>>> | # time rm -rf y
>>> |
>>> | real 5m18.034s
>>> | user 0m0.036s
>>> | sys 0m8.169s
>
>> Deletes on XFS is one area that is a little slower than other filesystems.
>> You can increase the log size during the creation of the filesystem and
>> also increase logbufs to 8 and that might help.
>
> Thanks for your suggestions.
>
> I also tried to increase the log size and logbufs mount option. This
> optimizes create and delete times to the above values (with default options
> both are around 9-10 minutes).
>
> The strange thing is that on a similar Dell machines using XFS, too,
> deletes take only ten seconds which would match user and system time.
>
> More than five minutes for deleting 100000 files where ext3 needs
> 3 seconds on the same machine is actually more than a little bit slower
> - to my mind there must be something wrong. JFS needs around 18 seconds.
>
> However I am not sure if the problem is hardware or software related.
> I've also tried to use the newest 3ware firmware - but this did not lead
> to an improvement.
>
> Ciao,
> Thomas
> --
> Thomas Kähn WESTEND GmbH | Internet-Business-Provider
> Technik CISCO Systems Partner - Authorized Reseller
> Im Süsterfeld 6 Tel 0241/701333-18
> tk@westend.com D-52072 Aachen Fax 0241/911879
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> Die Gesellschaft ist eingetragen im Handelsregister Aachen unter HRB 7608
> Geschäftsführer: Thomas Neugebauer, Thomas Heller, Michael Kolb
>
>

The benchmark:
$ time for i in `seq 1 100000`; do dd if=/dev/zero of=$i bs=1k count=20
>/dev/null 2>&1; done

1. Six 400GB SATA drives using SW RAID5:
real 6m24.411s
user 0m43.097s
sys 2m17.350s

2. Four Raptor 150 ADFD drives using SW RAID5:
real 3m16.962s
user 0m42.899s
sys 2m15.420s

3. Two Raptor 74GB *GD drives using SW RAID1:
real 3m19.241s
user 0m41.731s
sys 2m15.873s