Re: Possible performance problem introduced between kernel 2.6.15 and 2.6.17 on xfs code

[Francesco Degrassi <francesco.degrassi@emaze.net>]

I tried ext2, ext3, jfs, reiser3, vfat and the problem does not show up.
Anyway i discovered that if i create a regular file in an XFS partition,
create an XFS filesystem on it as if it was a regular block device, and
mount it with the loop device, the problem does NOT manifest.
So it seems to affect XFS filesystems on regular block devices only ?
I'm confused.


____________EXAMPLE________________
root@francesco:/tmp$ mount | grep tmp
/dev/sda7 on /tmp type xfs (rw)
root@francesco:/tmp$ dd if=/dev/zero of=bdev bs=1024 count=200000
root@francesco:/tmp$ mkfs.xfs -f bdev
root@francesco:/tmp$ mkdir mpoint
root@francesco:/tmp$ mount -o loop bdev mpoint/
root@francesco:/tmp$ time gnomevfs-copy \
/home/fdegrassi/Desktop/downloads/systemrescuecd-x86-1.2.18.iso mpoint/

real	0m3.998s
user	0m0.080s
sys	0m1.292s

root@francesco:/tmp$ time gnomevfs-copy \
/home/fdegrassi/Desktop/downloads/systemrescuecd-x86-1.2.18.iso /tmp


real	2m55.448s
user	0m0.100s
sys	0m1.984s

________________________END_____________________

Thanks for your time, Eric.

Francesco Degrassi

Eric Sandeen wrote:
> fdegrassi wrote:
>> The specific problem is related to gnome point-n-click only.
>> Anyway, I could be wrong, but i don't think it is a bug in gnome because:
>> 1. it affects specifically local XFS filesystems only
>> 2. the problem is not present on kernel 2.6.15 (I tested 2.6.17 and
>> 2.6.15, both on ubuntu 6.10)
>> 3. the problem does not manifest if i disable the call to
>> gnome_vfs_forget_cache, that, for what i understand, simply calls
>> fadvice POSIX_FADV_DONTNEED.
>>
>> More info can be found on gnome bugzilla entry.
>> Francesco Degrassi
>>
> 
> Thanks.  I didn't mean to suggest that it was necessarily a gnome bug,
> just wanted to narrow down the problem.  Do you have any idea if other
> filesystems on 2.6.17 also show this slowdown?
> 
> -Eric