# Kernel memory usage peer process



## kmalov (Oct 2, 2009)

Hi, i have a shared hosting server with about hundred clients (apache+mod_php). Everything was fine for some time, but now i have some clients, who use CPU mush more then other users. It's very hard to say, who do this with Apache+mod_php configuration.
And now i want to change server work model. I want to use sa, to collect information about system resources usage (CPU time. memory). But for this every user must run his php scripts from his own uid. There are several ways to do this, like SuExec or SuPHP. But for grate flexibility it would be nice to have unique apache for each client. With amd64 or PAE kernel it's passable. One apache with five children wheel use 6 * ~30Mb = 180Mb memory, so for hundred apaches a server with 20Gb of real memory can handle. (in real life with shared libraries a server will consume less memory). I think the bottleneck will be a kernel memory. How can i measure kernel memory needed for each apache process?


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## SirDice (Oct 2, 2009)

kmalov said:
			
		

> One apache with five children wheel use 6 * ~30Mb = 180Mb memory,


Where did you get those numbers? From top? IIRC it's not actually using 6 times that amount of memory as most of it is shared.


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## kmalov (Oct 2, 2009)

You right, is's very very rough estimate. I think one apache will differ for another only in php code, that is executed, in memory sense.

But the question is how much memory do kernel need to handle 1000 or more apaches?


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