Thomas Graichen writes:
>Robin Humble <rjh@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>* did you try kiocluster's (only work with ide or scsi not with md
> or lvm) - no idea if it might help -> mount -o kiocluster ...
No, I didn't try this. I need to use RAID in the end so it's not
much use to me... :-/
>* the other good lines posted often here (but i don't think they
> will help here) -> mount -o logbufs=4,logbsize=32768 ...
>* creating the filesystem with a bigger journal is also a good idea
> for real workload (ok - i think not in this case too - because
> here is not much metadata to journal :-)
> -> mkfs -t xfs -l size=32768b ...
yeah - good idea - I could try that, but like you say - I don't know
why they would help. It's just one file being written.
>* did you try the same with an up kernel? - maybe some smp locking
> thing somethere
I just tried the 'dd' between my home machines (server is
Athlon700/ATA66 single processor, single disk, RH6.2, older 2.4.2 cvs
kernel, and the client is p120 laptop RH6.2) and found much the same
behaviour. However because I only have a 10Mbit network at home, the
nfsd loads didn't get high enough to choke the transfers like they do
with the 100Mbit connections at work. At home, writing to either XFS
or ext2 with a dd achieved about ~1MB/s which is what you'd expect.
time dd if=/dev/zero of=/mnt/xfs/bigFile bs=1M count=256
takes ~270s or so.
For the XFS writes, the nfsd load was about 25% total (4 daemons,
~5.5% each), and it was only about 3% total for ext2 (<1% per nfsd).
So I guess this problem only really shows up on 100Mbit or greater
networks where the traffic to the daemons is 10x higher.
So yeah, because I see roughly the same nfsd load behaviour on a
single procesor box, think that SMP isn't much of an issue, but yes I
should test it. Is there a way to boot an SMP kernel in uni-processor
mode or should I recompile?
Your bonnie setup (in the other email) is possibly a bit flawed in
that it writes only 128M files and the server has 128M of memory, so
in theory the server doesn't have to write to disk at all. Could you
maybe try it again with a file size that's more than twice the server
memory size? That's what bonnie++ tells you to do anyway, I don't
know about bonnie.
Are you using NFSv3 on the server/client? nfsstat will let you know.
cheers,
robin
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