Date: Sun, 2 Mar 2003 07:11:12 -0800 (PST) From: Mike Harding <mvh@ix.netcom.com> To: freebsd-questions@freebsd.org Cc: tom@motorsport.com Subject: Re: Apache and shared memory Message-ID: <20030302151112.27D475296@netcom1.netcom.com>
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When people talk about optimizing mod_perl shared memory, they are not referring to System V type shared memory as seen by ipcs. They are talking about memory shared by virtue of a process fork - this is effectively read only memory. The net effect is that a process may appear to be 20 meg, but may only use 2 or 3 meg, say. It has been difficult to monitor 'unshared' memory use in FreeBSD as freebsd has traditionally reported via getrusage() as an 'integrated' unshared memory use which is more related to the old school process accounting than it is to the actual unshared memory use - this may have changed in -CURRENT or recent -STABLEs. Linux reports the unshared memory directly via gtop which is a lot more convenient. I wish (hint hint) that there was a sysctl to handle this... There are other tricks you can do to maximize memory use, such as putting the php and perl servers, and image servers on separate apache processes, and proxying between them, rather than running php and mod_perl on the same server, and adjusting the (Min/Max)SpareServers to reap apache process during quieter times. The main thing to do with mod_perl is to pre-load all of the perl modules during apache startup so that the modules are shared rather than being loaded separately into each apache process. http://perl.apache.org has some excellent documentation about this. Also Apache::SizeLimit can be useful for mod_perl based systems. Tuning apache can be a lot of... fun! Hope this helps, - Mike H. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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