Re: [linuxperf] High load under Apache1.3.3/mod_perl 1.16/Linux 2.2.7 SMP

["Mike Whitaker" <mike@cricket.org>]

This is getting into heavy Linux, so I've dropped modperl from thw cc:

> I thought folks'd like a progress report, since at least one discovery
> (while perhaps not surprising) is educational.
>
> We have a test machine up with Linux kernel 2.3.3 (which has a *different*
> wake-one scheduler patch) which I'm tossing hits at from ApacheBench. Pure
> static pages, and it flies: 600+ hits a second for a small gif (even with a
> concurrency of 300). [N.B 2.2.8+andrea1 hung on one of our live servers
> after 20 mins of serving pages (and like a fool I picked one of the servers
> in a facility without 24x7 access/callout cover *wry grin*)]

We're up with 2.3.3 plus Andi Kleen's tcp_do_sendmsg patch plus Apache
sleeping in accept() on one production server, and comparing it against a
2.2.7 plus tcp_do_sendmsg patch plus Apache sleeping in flock(). Identical
systems (dual PII450, 1G, two disk controllers).

As far as I can *tell*, the wake-one patch is definitely doing its stuff:
the 2.2.7 machine still has cycles of load into three figures, and the 2.3.3
machine hasn't actully managed a load of 1 yet.

UNFORTUNATELY, observation suggests that the 2.3.3 machine/Apache
combination is dropping/ignoring about one connection in ten, maybe more.
(Network error: connection reset by peer.)

As far as I can *see* there's nothing in either Apache error log (for either
httpd), and it is quite often missing the proxy reauest from localhost to
localhost:8989 (proxying the mod_perl ad).

Thoughts?
--
Mike Whitaker /  Tel: +44-1733-766619 | Email: mike@cricket.org
CricInfo Ltd /   Fax: +44-1733-346287 | Emergency: mike@sms.cricket.org
Technical   / Mobile: +44-7971-977375 | Mobile: mike@mobile.cricket.org
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