[svlug] HELP! Apache performance on a Compaq Presario

[Seth David Schoen]

Dave Zarzycki writes:

> At work, someone requested to see the performance of Linux as a web server
> compared to our own OS as a web server. I thought that Linux would be a
> quick win, but to my suprise, something is terribly wrong. I need some
> help to show the superiority of Linux!
> 
> Setup:
> 
> Compaq Presario 4880 (400MHz PII)
> 192MB of RAM
> 10GB hard drive (IDE, this is a desktop machine from marketing)
> 10/100 EtherExpress
> 4 port 10/100 DEC 21140 card
> Red Hat Linux 5.1 plus all updates
> 
> The performance is roughly 50 connections per second. I know linux can go
> faster, so what gives? The load average never passes over one and the idle
> time is always above 90%. I've tried both WebBench (on PCs, yuk), and
> WebStone (running on AIX). I've tried both Apache 1.2.1, which comes
> with Red Hat Linux 5.1, and Apache 1.3.1. I've even tried the 2.1.119
> kernel to see if that made things better, but it was no different. Lastly,
> I tried a silly little web server that I wrote in a few hundred lines of
> C, and it experianced the same problems. (In other words, it's not the
> server...)
> 
> Does anybody have any idea what's going on? I don't think the sniffer will
> tell me much. Are there any kernel options I can tweak?

If your load average is only one, and your CPU time is underutilized, and you
have free RAM, you should be running more copies of Apache.  In httpd.conf,
you should look at these defaults

MinSpareServers 8
MaxSpareServers 20

# Number of servers to start --- should be a reasonable ballpark figure.

StartServers 10

# Limit on total number of servers running, i.e., limit on the number
# of clients who can simultaneously connect --- if this limit is ever
# reached, clients will be LOCKED OUT, so it should NOT BE SET TOO LOW.
# It is intended mainly as a brake to keep a runaway server from taking
# Unix with it as it spirals down...

MaxClients 150

and change them all higher.  If you're dealing with 50 connections per second,
they should probably be substantially higher.  The reason that these are set
relatively low is to prevent Apache from consuming excessive amounts of
system resources on a multi-purpose workstation; on a dedicated server, you
can run more Apaches at once and so give it more of the system's time.

I hope this makes a difference in your performance.

-- 
   Seth David Schoen L&S '01 (undeclared) / schoen at uclink4.berkeley.edu
Magna dis immortalibus habenda est atque huic ipsi Iovi Statori, antiquissimo
custodi huius urbis, gratia, quod hanc tam taetram, tam horribilem tamque
infestam rei publicae pestem totiens iam effugimus.  -- Cicero, in Catilinam I

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