Posted by Atelier Fabien on 10/24/05 22:24

I'm no fs_usage expert, so I have no idea on how to profile IO with
it. I do know/see very high CPU usage when running PHP. The httpd
process takes up to 70% of CPU capacity. This 'peak' can take about 4
to 8 seconds for example.

So I'm tempted to rule out DNS issues. Also because static (html)
files and simple php files (without includes) are very fast.

Any tips on fs_usage etc. are still welcome though.

> I haven't had any problems with slowdowns on 10.4. Usually when
> there are slowdowns on the Mac like you indicate, it has something
> to do with DNS lookups being performed. Apple seems to be having a
> hard time getting this right. You could problem find a ton of posts
> on very slow ssh on the Apple forums that have to do with DNS.
>
> Have you figured out what the computer is doing when a page is
> taking that long? You mention it seems to point to an IO problem,
> have you used iostat (or fs_usage) to verify it's disk IO? My first
> guess is something with the network and you have to wait for a
> lookup, response or timeout, which is why it's taking at a minimum
> 10 seconds. Again, I would check DNS first, the most obvious being
> Apache resolving IP addresses for the log (don't do it).

[Back to original message]