Re: high cpu utilization

Ok. I can upgrade the kernel. When is 1.3 scheduled to be "stable"

On Feb 12, 2008 3:51 PM, Willy Tarreau <w#1wt.eu> wrote:

> On Tue, Feb 12, 2008 at 11:56:55AM -0700, Dan Zubey wrote:
> > For logging to work, you need to enable syslog with the -r switch, and
> > then restart syslog.
>
> exactly :-)
>
> > Check out debug mode, but Willy will have additional ideas in a bit
> here.
>
> The early 2.6 kernels had *horrible* CPU usage patterns. You're lucky to
> just see 100% CPU, I've seen machines pausing several seconds, with vmstat
> freezing. The biggest of these troubles started to get fixed around 2.6.16
> ,
> then slightly better with 2.6.18, and finally disappeared with the new CFS
> scheduler in 2.6.23.
>
> What I've also observed was a perfectly regular process showing sine waves
> in CPU usage, from long periods at 0% to long periods at 100%, back and
> forth. I know the load was perfectly stable because it was regulated by
> an external injection system which itself was monitored, and all
> indicators
> on the network reported a 3-digit stability, while the 2.6 machine in the
> middle was oscillating between 0 and 100%. Obviously, even if 100% had
> been possible, 0 was not possible because the work it had to do made it
> run at about 25%, which must be noticeable.
>
> Now, don't get me wrong. I'm not saying that there does not exist a
> problem
> with 1.2.17 which occasionally brings the CPU to 100%, what I'm saying is
> that *measuring* CPU on such an awfully crappy 2.6.9 means absolutely
> nothing.
>
> I would propose something :
> - download and build 2.6.23.16, and reboot the machine on it.
> Configuration
> may be quite long because it has evolved a lot since, but you can also
> download a recent pre-built fedora kernel for instance.
>
> - also test with a more recent haproxy version (latest snapshot or
> 1.3.14.2).
>
> If the problem definitely disappears with either change, it means that the
> old version is the culprit. If the problem remains with 2.6.23.16, it
> means
> either that the load is really huge (gigabit, regex?) or that it's a yet
> undiscovered bug in haproxy. But judging by many people's usage, even high
> loads should not push your CPU to 100%.
>
> Regards,
> Willy
>
>
Received on 2008/02/12 22:39