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Apache HTTP Server Version 1.3
Running a High-Performance Web Server for HPUX
Date: Wed, 05 Nov 1997 16:59:34 -0800
From: Rick Jones <raj@cup.hp.com>
Reply-To: raj@cup.hp.com
Organization: Network Performance
Subject: HP-UX tuning tips
Here are some tuning tips for HP-UX to add to the tuning page.
For HP-UX 9.X: Upgrade to 10.20
For HP-UX 10.[00|01|10]: Upgrade to 10.20
For HP-UX 10.20:
Install the latest cumulative ARPA Transport Patch. This will allow you to configure the
size of the TCP connection lookup hash table. The default is 256 buckets and must be set to a
power of two. This is accomplished with adb against the *disc* image of the kernel. The
variable name is tcp_hash_size. Notice that it's critically important that you use
"W" to write a 32 bit quantity, not "w" to write a 16 bit value when
patching the disc image because the tcp_hash_size variable is a 32 bit quantity.
How to pick the value? Examine the output of ftp://ftp.cup.hp.com/dist/networking/tools/connhist
and see how many total TCP connections exist on the system. You probably want that number
divided by the hash table size to be reasonably small, say less than 10. Folks can look at
HP's SPECweb96 disclosures for some common settings. These can be found at http://www.specbench.org/. If an HP-UX system was
performing at 1000 SPECweb96 connections per second, the TIME_WAIT time of 60 seconds would
mean 60,000 TCP "connections" being tracked.
Folks can check their listen queue depths with ftp://ftp.cup.hp.com/dist/networking/misc/listenq.
If folks are running Apache on a PA-8000 based system, they should consider "chatr'ing"
the Apache executable to have a large page size. This would be "chatr +pi L
<BINARY>." The GID of the running executable must have MLOCK privileges.
Setprivgrp(1m) should be consulted for assigning MLOCK. The change can be validated by running
Glance and examining the memory regions of the server(s) to make sure that they show a
non-trivial fraction of the text segment being locked.
If folks are running Apache on MP systems, they might consider writing a small program that
uses mpctl() to bind processes to processors. A simple pid % numcpu algorithm is probably
sufficient. This might even go into the source code.
If folks are concerned about the number of FIN_WAIT_2 connections, they can use nettune to
shrink the value of tcp_keepstart. However, they should be careful there - certainly do not
make it less than oh two to four minutes. If tcp_hash_size has been set well, it is probably
OK to let the FIN_WAIT_2's take longer to timeout (perhaps even the default two hours) - they
will not on average have a big impact on performance.
There are other things that could go into the code base, but that might be left for another
email. Feel free to drop me a message if you or others are interested.
sincerely,
rick jones
http://www.cup.hp.com/netperf/NetperfPage.html
Apache HTTP Server Version 1.3
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