[squid-users] Hyper-threading, SSD vs HDD, CentOS vs Ubuntu Server and best performer Squid version

[Amos Jeffries]

On 29/10/18 11:13 AM, manuelfgarcia wrote:
> According to https://wiki.squid-cache.org/BestOsForSquid :
> "CPU speed and core count:
> few faster cores are better than many slow cores. SMP Squid can currently
> operate most efficiently with 4-8 cores of 3GHz or more. multi-tenant
> installations are better for machinery with very many cores.
> only the physical cores are useful, hyper-threaded "cores" can actually be
> worse.
> 
> Is that statement still up to date or is is it no longer the case from any
> specific version of Squid?
> 

It is still true and correct.


> Considering the statement that "hyper-threaded "cores" can actually be
> worse.", what is supposed to handle faster and concurrent connections on
> reverse proxy mode?

Reverse-proxy mode gains its performance benefits through only having to
service a limited range of URLs. Which means more predictability and
objects do not get evicted from memory cache quite as often as from
other proxies. Memory is faster than disk or network. Nothing to do with
CPU(s).


> - Intel Xeon X3430 (2.40GHz, 2,80 GHz turbo, 4 physical cores, 4 threads)
> vs.
> - Intel Xeon E3-1230-V6 3.40GHz (3.50 GHz, 3.90 GHz, 4 physical cores, 8
> threads)
> 
> On another note, what is supposed to handle faster and more concurrent
> connections on reverse proxy mode between these options?:
> 
> - SSD vs HDD
> 

These are disk drives. Not networks. Disks have nothing to do with
"concurrent connections". Squid can handle as many concurrent
connections as your servers TCP stack allows it to. No more, no less.


Squid performs random-access I/O to on-disk caches. With an order of
magnitude or so higher than normal write accesses. These non-normal I/O
patterns prevent typical disk controllers I/O prediction models from
working efficiently.

So be aware that whichever disk type you choose will have its lifetime
reduced to some fraction of what any manufacturer specs' it as being
capable of. How much depend on your specific traffic.

SSD are still faster hardware than HDD. But also typically wear out
faster and have smaller content capacity. So it is a matter of whether
you can afford the budget to replace SSD or HDD as they wear out. And
you can easily change between them at any time if you want to experiment.


> - CentOS 7 vs CentOS 6 vs Ubuntu Server 16.04 vs Ubuntu Server 18.04
> 
> - Squid 3.1 vs 3.5 vs 4.x...
> 

Squid-3.x are officially deprecated by Squid-4 being published. Similar
deprecation situations apply for the OS you mention.

A good rule of thumb for any new installation is to start with the
latest tech you are able. It will have the longest support / warranty
period as measured from the day you decide to put it into service. If
you start with tech that is old, you are cutting your support timespan
by that much.

Another (possibly conflicting) rule of thumb, is to reduce the amount of
change you are going to have to learn. If you are already familiar with
a particular OS go with that while you learn how to operate the Squid
part of the system. Squid operates approximately as well in any OS -
excluding Windows, which sadly imposes a few severe network limitations.


HTH
Amos