Re: Network performance degradation from 2.6.11.12 to 2.6.16.20

On Mon, Jun 19, 2006 at 05:24:31PM +0200, Andi Kleen wrote:

quoted

If you use "pmtmr" try to reboot with kernel option "clock=tsc".

That's dangerous advice - when the system choses not to use
TSC it often has a reason.

I just found out that TSC clocksource is not implemented on x86-64.
Kernel version 2.6.18-rc7, is it true?

I've also had experience of unsychronized TSC on dual-core Athlon,
but it was cured by idle=poll.

quoted

On my Opteron AMD system i normally can route 400 kpps, but with 
timesource "pmtmr" i could only route around 83 kpps.  (I found the timer 
to be the issue by using oprofile).

Unless you're using packet sniffing or any other application
that requests time stamps on a socket then the timer shouldn't 
make much difference. Incoming packets are only time stamped
when someone asks for the timestamps.

It seems that dhcpd3 makes the box timestamping incoming packets,
killing the performance. I think that combining router and DHCP server
on a same box is a legitimate situation, isn't it?

~
:wq
                                        With best regards, 
                                           Vladimir Savkin.