Re: [squid-users] Multi thread or Not multi thread processor

On Mon, Sep 01, 2008 at 02:20:47AM -0700, elsergio wrote:
> Which option is better for using Squid as a Load Balancer?
>
> a) Multi thread processor.
> b) Non Multi thread processor.

Non multi-thread/core processor is only to be preferred if you can
get a faster processor at the same price, i.e. if you can trade
processor pipelines for raw speed. Even then, you'd probably only
want to do that if you're gaining quite a bit of speed.

Squid itself is a single-process, single-threaded application, so
cannot take advantage of more than one processor pipeline.
Theoretically then, a faster CPU that can only run one
thread/process at a time is better than a slower one which can run 2
or more threads at the same time simply because squid itself can
only make use of a single pipeline.

However: many (most?) squid configurations make use of external
processes, such as URL rewriters and authentication helpers. Since
they're separate programs they can take advantage of parallel
execution provided by the CPU. You can also use diskd or aufs to
move the disk access to another process (though that's more I/O
intensive than CPU intensive).

In addition, even a dedicated server will have some background
processes happening (time sync, admin logins, logging, etc.).
Therefore, you're almost guaranteed to have other processes that
would like to run at the same time as squid regardless of your
squid configuration.

Therefore, my best guess is that dual-core CPUs are the way to go.
Additional cores will probably only be helpful if you have lots of
additional helper processes running simultaneously, or if the server
is doing things besides running squid.

Another thing to consider is running multiple squid instances on the
same server. In that case, more cores (or physical CPUs) will
definitely help, but whether or not it's feasible depends on what
you want to do and how you want to do it.

Okay, after having written all that I managed to find the recent
thread which discussed this in some detail, so you might find this
to be worth a read:

http://www.archivum.info/squid-users@squid-cache.org/2008-07/threads.html#00454
Received on Mon Sep 01 2008 - 10:11:14 MDT