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

I use 8 cores CPU for ISP level Squids. Squid's external apps like DNS
resolvers, I/O (especially if you use aufs/diskd/coss), logging, it's
always a good idea to get more than 4 cores so Squid wouldn't lock for
long on these external apps to reply back to the main process.

On Mon, Sep 1, 2008 at 1:11 PM, Michael Alger <squid_at_mm.quex.org> wrote:
> 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
>

-- 
Sincerely,
Haytham EL-KHOUJA
haytham_at_khouja.net