Extreme slowness with xfs [WAS: Re: Slowness with new pc]

[Justin Piszcz]

On Mon, 24 Nov 2008, Stian Jordet wrote:

> sø., 23.11.2008 kl. 17.25 -0500, skrev Justin Piszcz:
>> As the original posted stated:
>>
>> 1. please post dmesg output
>> 2. you may want to include your kernel .config
>> 3. xfs_info /dev/mdX or /dev/device may also be useful
>> 4. you can also check fragmentation:
>>     # xfs_db -c frag -f /dev/md2
>>     actual 257492, ideal 242687, fragmentation factor 5.75%
>> 5. something sounds very strange, I also run XFS on a lot of systems and
>>     have never heard of that before..
>> 6. also post your /etc/fstab options
>> 7. what distribution are you running?
>> 8. are -only- the two fujitsu's (raid0) affected or are other arrays
>>     affected on this HW as well (separate disks etc)?
>> 9. you can also compile in support for latency_top & power_top to see
>>     if there is any excessive polling going on by any one specific
>>     device/function as well
>
> 1 & 2: Oh, sorry I forgot to attach dmesg and config in the last mail.
>
> 3:
> root at chevrolet:~# xfs_info /dev/sdb1
> meta-data=/dev/sdb1              isize=256    agcount=32,
> agsize=11426984 blks
>         =                       sectsz=512   attr=0
> data     =                       bsize=4096   blocks=365663488,
> imaxpct=25
>         =                       sunit=0      swidth=0 blks
> naming   =version 2              bsize=4096
> log      =internal               bsize=4096   blocks=32768, version=1
>         =                       sectsz=512   sunit=0 blks, lazy-count=0
> realtime =none                   extsz=4096   blocks=0, rtextents=0
>
> 4:
> root at chevrolet:~# xfs_db -c frag -f /dev/sdb1
> actual 380037, ideal 373823, fragmentation factor 1.64%
>
> 6: The only mount-option is relatime, which Ubuntu adds automatically.
> Hmm. I haven't tried to mount without that option. Well, didn't help
> without it neither, tried just now.
>
> 7: Ubuntu 8.10 Intrepid. This is a new system, and it has never run
> anything other than Intrepid. This affects both the standard kernel, and
> the vanilla 2.6.27.7 that I have compiled (dmesg and config attached is
> from that kernel). Have also tried both 64 bit and 32 bit (just for fun)
>
> 8: I'll explain my setup a little bit more. I explained the hardware in
> my first post. But I have the two Fujitsu SAS disks in RAID-0,
> with /dev/sda1 as root, and /dev/sda2 as home. Earlier they were both
> xfs, and dog slow. I have now converted both to ext3, and everything is
> normal. In addition I have four Seagate ST3500320AS 500GB SATA disks in
> hardware RAID-5 on the same controller. This 1,5TB array is still xfs.
> It also had and has the same symptoms.
>
> 9: I don't know how to do that. But what ever it is, it doesn't happen
> with ext3...
>
> Thanks for looking into this!
>
> Regards,
> Stian
>

While there still may be something else wrong, the first problem I see is 
your sunit and swidth are set to 0.

Please read, a good article on what they are and how to set them:
http://www.socalsysadmin.com/

Justin.