Re: Server response time discrepancy.

On Sun, Jun 29, 2008 at 09:39:38PM -0600, Unai Rodriguez wrote:
> > Unai,
> >
> > what kernel version are you running and what is the output of "cat
> /proc/sys/net/ipv4/tcp_frto"?
>
> ----------------------------------
> uname -a
> Linux lb1-dp-vm 2.6.8-3-686 #1 Tue Dec 5 21:26:38 UTC 2006 i686 GNU/Linux

  ^^^^^^^^^^^^^^^^^^^^^^^^^^^

could you check with "vmstat 1" that you're not approaching 50% CPU consumption on any of your old 2.6 kernels when the problem happens (servers and proxies) ? I know about a pathological CPU usage pattern for all 2.6 kernels using the scheduler before CFS (<2.6.23), which could cause large pauses to certain processes, of up to 30 seconds, though they have shrinked to about 3-4 seconds around 2.6.18. And haproxy was very good at producing those patterns. It *is* the reason why I've been staying away from 2.6 for years.

Regards,
Willy Received on 2008/06/30 22:08