Re: Slow directory listings under light load
I just changed the scheduler from the default cfq (which is said to
have the best multiuser performance) to anticipatory and then
deadline. Wow, what a difference. Anticipatory takes about 10 seconds
to list a directory of 5,000 items under load from dd, and deadline
takes about 5 (yes, i dropped the caches and buffers first).
Is this normal behavior with cfq? I was under the assumption that it
would be most ideal for this type of workload.
On Nov 8, 2007 11:42 PM, Ryan Bair <ryandbair@gmail.com> wrote:
> I have Debian Etch AMD64 installed on a Dell PowerEdge 1950, connected
> to a MD1000 (SAS/SATA array) via a PERC5/e SAS controller. The array
> is RAID5. The whole drive is LVM, 9TB are one big XFS partition.
>
>
> Linear reads/writes are very fast, directory listings are also fast.
> However, if the disk is under any kind of load (say someone
> downloading a file at 20MB/s) long directory listings (ls -l) get
> extremely slow. Listing a directory of 1000 files can take 5 minutes.
> Normal directory listings remain reasonable.
>
> If I strace ls -l, I notice its stopping at each getxattr() call for a
> split second, seems that's where it is wasting all of its time.
>
> Upon a recommendation at #xfs, I tried using attr2 via the mount
> option. xfs_db -c version shows:
> versionnum [0xb094+0x8] = V4,ATTR,ALIGN,DIRV2,EXTFLG,MOREBITS,ATTR2
>
> The whole install is pretty vanilla. Any thoughts on why this system
> can't handle this type of load? Please cc me as I am not subscribed to
> this list.
>
> Thanks
>
Reply to: