Re: Strange delete performance using XFS

Justin Piszcz
2007-04-04T13:58:03Z

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On Wed, 4 Apr 2007, Justin Piszcz wrote:

>
>
> 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
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>>
>>
>
> I am running some benchmarks with SW raid and will prevent my findings
> shortly.

Removal tests coming shortly, benchmarking is always interesting.