2 x quad-core system is slower that 2 x dual core on FreeBSD

Ivan Voras ivoras at freebsd.org
Mon Nov 19 05:46:34 PST 2007

Alexey Popov wrote:
> Hi.
> I have a large pool of web backends (Apache + mod_php5) with
> 2 x Xeon 3.2GHz processors and 2 x Xeon 5120 dual-core processors. The
> workload is mostly CPU-bound. I'm using 6-STABLE-amd64 and also tried

If you haven't tried mod_fcgid, give it a try - it can dramatically
benefit PHP applications. And with mod_fcgid, you can use apache with a
multi-threaded MPM (i.e. worker-mpm).

> Now I'm trying to use new hardware with 2 x Xeon 5320 (quad-core), but
> it can not work under the same load as dual-core. It shows up to 80%
> system CPU load in top:

On what version of FreeBSD is this? If it's 6-STABLE, this might be

> CPU states:  9.5% user,  0.0% nice, 79.9% system,  1.2% interrupt,  9.5%
> idle

Can you try hitting "S" to see if a kernel process is gobbling up CPU time?

> Here's the output from 2xdual-core backend running under the same load
> and with the same software:

> CPU states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  0.0%
> idle

This line is bogus - where is the load?

> What can I do to make FreeBSD run faster on many-CPU systems???

Except for trying 7-STABLE, there's not much you can do.

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