[squid-users] SMP mode, workers, cache_dir with conditional

[juju]

 Hello !
Thank you very much Alex and AmosI have 2 real cores so it will be good.

on http://www.squid-cache.org/Doc/config/cache_dir/  (available in: 4   3.5   3.4   3.3   3.2   2.7   3.1   3.0   2.6)   :"In SMP configurations, cache_dir must not precede the workers option and should use configuration macros or conditionals to give each worker interested in disk caching a dedicated cache directory"

Perhaps it would be good to specify for which version and which cache_dir type this note is for.
Best regards 
    Le mercredi 10 octobre 2018 à 19:38:55 UTC+2, Alex Rousskov <rousskov at measurement-factory.com> a écrit :  
 
 On 10/10/2018 09:10 AM, Amos Jeffries wrote:
> On 11/10/18 3:01 AM, juju wrote:
>> Hello,
>> Sorry if this question has already been posted ( I can't check as the
>> "Search Function" is currently not working )
>> I'm running squid-3.5.20 on Amazon Linux 2018.03. 2 cores with 8 GB
>> My squid is currently working but only on 1 core.
>> I which to use the 2 cores. I understood that I have to use workers in
>> squid.conf with separate cache directory.

> This is not quite correct.

> Per-worker configuration is only required for features which are not yet
> SMP-aware.


Just a couple of additional clarifications, not contradicting what Amos
has said:


> The rock cache type *is* SMP-aware, so one directory can be shared by
> workers.

"can be" and "must be". We do not support worker-specific cache_dirs.

In case of rock cache_dirs, I do not know for sure what would happen if
cache_dirs are configured on a per-worker basis, but I suspect that
there will be no disker processes to serve them. At best, you will get
no disk caching at all.


> The UFS/AUFS/diskd cache types are not SMP-aware yet, so they do need
> separate directories per-worker currently.

... but worker-specific cache_dirs are not supported, will violate HTTP
rules, etc.


> Since you are using only rock type caches you do not have to do anything
> special for SMP to work.

... with your simple configuration that does not use SMP-unaware features.

In fact, with rock cache_dirs, you do not even have to specify multiple
workers to get SMP Squid -- by default, Squid will run in SMP mode if
you have one worker (default) and at least one rock cache_dir. However,
multiple workers may be necessary to better utilize multicore CPUs.

Beware of hyperthreading: Do not expect two workers, each showing 80+%
CPU utilization to be able to share a single physical CPU core
efficiently. I do not know whether your two cores are hyperthreaded or real.

N.B. To search the mailing list archives, consider using your favorite
search engine. Many would accept a site:lists.squid-cache.org restriction.

Alex.
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