RE: [squid-users] Squid 3.0 and Linux 2.6 kernel tweaks

From: Henrik Nordström <henrik_at_henriknordstrom.net>
Date: Fri, 19 Feb 2010 22:55:41 +0100

fre 2010-02-19 klockan 12:54 -0800 skrev Andy Litzinger:

> We run with stock kernels from CentOS/RHEL so I guess I meant in those the kernel and shell fd limits are way higher.

Are you sure they are by default?

It's easy to configure anyhow.

> > On must systems the default is whatever the ulimit is set to when you
> > run configure.
>
> Great, thanks. Is there any way to confirm this on a compiled squid, or is it best practice to define the value upon compilation?

Unfortunately not.

> I'm not sure I understand what you mean here. How/where does squid
> get this value? And I suppose I should have said checking/increasing
> the kernel file descriptor limits (/proc/sys/fs/file-max) and the
> shell file descriptor limits (ulimit -n).

ulimit is the primary limit.

file-max is related, but the system global limit. Should be bigger than
ulimit obviously.

Squid reports it's current limit in cache.log at startup.

> I understand that TIME_WAIT and ephemeral port increases are not
> usually needed, but I am concerned with the case of reverse proxying
> thousands of very short lived requests per second. I suppose it's
> likely for the service to die long before I exhaust available
> resources, but at least I'll know I won't be bottlenecking anything.

Again it depends on the traffic pattern. The important number for
TIME_WAIT & ports is the number of connections Squid makes to the web
servers, not really the number of connections it is receiving.

> I appreciate your feedback! I do think it would be valuable for this
> type of qualified information to make it into the wiki somewhere.
> I'll look for the process to do so, but if you have any hints as to
> where this info should live I would love to hear them.

Instructions how to contribute to the wiki is given on the wiki first
page, second paragraph.

  http://wiki.squid-cache.org/

Regards
Henrik
Received on Fri Feb 19 2010 - 21:55:50 MST

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