Re: major network performance difference between 2.4 and 2.6.2-rc2

Andrew Morton
2004-02-04T20:56:39Z

Jim Faulkner <jfaulkne@ccs.neu.edu> wrote:
>
>
> I am still experiencing severely degraded network performance under
> 2.6.2-rc3 and 2.6.2-rc3-mm1.

A kernel profile is needed.

> Based on some kernel output, I think this
> problem may be related to Gerd Knorr's input patches, so I am CCing him on
> this e-mail.

Sounds unlikely.

> Additionally, while large network transfers are going on, both ksoftirqd/0
> and events/0 start going crazy, putting a huge load on my system:
>
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 3 root 35 19 0 0 0 S 45.9 0.0 0:46.98 ksoftirqd/0
> 6 root 5 -10 0 0 0 S 43.3 0.0 1:56.63 events/0
> 12008 dogshu 15 0 4800 2356 3828 S 5.3 0.2 0:05.98 proftpd
> 12 root 15 0 0 0 0 S 0.3 0.0 0:00.41 pdflush
> 9778 root 16 0 5888 1724 5516 R 0.3 0.2 0:00.12 sshd
>
> the load before that network transfer was 0.01, and the load after the
> network transfer was 1.45.

Could be a networking problem, but boy that's a lot of CPU time.

Please, do this:

- Boot with `profile=1' on the kernel command line

sudo readprofile -r
sudo readprofile -M10
time <whatever command it is that is causing the problem>
readprofile -n -v -m /boot/System.map | sort -n +2 | tail -40 | tee ~/log

Making very sure that /boot/System.map is the correct map file for the
currently-running kernel.

Thanks.