Re: NFS server delays on NSLU2
On Thu, 2007-03-29 at 11:19 +0200, Marcus Better wrote:
> I'm running an NFSv4 server on my slug with kernel 2.6.18-4-ixp4xx, using
> GSSAPI authentication and with autofs on the client. In general it works,
> but I often experience delays when (auto)mounting partitions. For example,
> ls /mnt/nfs/slug/files
> on the client when the share is not yet mounted results in a long delay
> (perhaps minutes). If I interrupt the command and do
> ls /mnt/nfs/slug
> to list all the shares on the server, it often only shows one share, the one
> that I tried to access. The remaining ones show up only after a few
> After that it usually works well without noticeable delays for the rest of
> the session.
> Since it's a somewhat complex setup I'm not sure how to debug it. The only
> thing I know is that I have another NFSv4 server on a larger i386 system
> with an identical setup, and it works without delays, with exactly the same
> client. So I'm half-suspecting that it may have something to do with the
> new IXP network driver.
I would say that if it _is_ the network driver, you should notice delays
in lots of networked protocols, like ssh, ftp, or other. You can use
tcpdump to check on the network traffic between server and client.
I don't know what services you're running on your slug, but it has only
32M of memory, so generally, all unused daemons are swapped out as time
passes by. For example, I run a web server with php and mysql as well as
samba, imapd and sshd. If I've had web traffic but not samba for a
while, mounting a samba share takes a moment for samba to be swapped
right in. If I make heavy use of samba, loading a web page can take
ages, especially if php starts consuming 10M+ of memory.
To make sure, run top and look at the idle and wait statistics. You
might also want to sort processes by memory usage (press '>' once). If
you have lots of wait time, your disk is probably very busy swapping
things around. To make sure that it _is_ swapping, install atop and run
that (look at paging: pages in/out). But take notice: atop starts a
daemon which takes up 2M+ of resident memory and runs all the time. So
after testing your setup, remove the package to reclaim your 2M+ memory
(or disable the atop service).