2003-06-23 05:06:07

by jurriaan

[permalink] [raw]
Subject: 2.5.72: system unusable during upload to slow nfs-server

I rsync some directories to a nfs-mount on a very large harddisk on a
non-udma system. This system can read/write data at about 3-4 megabyte
per second.

If I rsync in 2.4, all happens as you'd expect: the update doesn't go
fast, but the interactivity of the kernel is good while it's running.


In 2.5.7x, it runs really fast for a while (rsync mentions 30 mb/s), and
after a while slows down. Then, a mutt-session on another console lags
about 10-30 seconds when you press a key. top gives 98% IO-wait.

The nfs-server runs 2.4.21-rc7, and the mount is like this:

server:/backup_big on /mnt type nfs (rw,wsize=16384,rsize=16384,hard,intr,posix,tcp,addr=x.x.x.x)

The local machine I'm working on is an Athlon XP-2600 with pre-empt. The
network is 100 mbps with full-duplex. I'm using NFS V3 on both sides.

The interactivity in 2.4 is good, in 2.5.7x is very bad.

Any hints?

Thanks,
Jurriaan
--
Baldrick, I would advise you to make the explanation you are about to give
phenomenally good.
The Black Adder
Debian (Unstable) GNU/Linux 2.5.72 4112 bogomips load av: 2.09 1.65 0.77


2003-06-23 06:49:23

by Andrew Morton

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Subject: Re: 2.5.72: system unusable during upload to slow nfs-server

Jurriaan <[email protected]> wrote:
>
> I rsync some directories to a nfs-mount on a very large harddisk on a
> non-udma system. This system can read/write data at about 3-4 megabyte
> per second.
>
> If I rsync in 2.4, all happens as you'd expect: the update doesn't go
> fast, but the interactivity of the kernel is good while it's running.
>
>
> In 2.5.7x, it runs really fast for a while (rsync mentions 30 mb/s), and
> after a while slows down. Then, a mutt-session on another console lags
> about 10-30 seconds when you press a key. top gives 98% IO-wait.

Please send a `vmstat 1' trace, and the contents of /proc/vmstat
taken when the thing is being sluggish.