Re: Process size..

Hi there. I've been following this thread with some interest, as it
seems
to go contrary to what has worked best for me.

I am running Squid 2.2_STABLE5 on a dual-processor Ultra60 with 1GB of
memory. I tried different cache_mem settings, and the one that has given
me the greatest performance (ie. lowest avg transaction time and highest
cache hit rate) was a setting of "cache_mem 384 MB". It swaps about
100MB
to HDD, but that doesn't appear to hurt performance too much. Here is
how
the system is configured:

        Squid 2.2_STABLE5 on Sun Ultra 60 with 1GB RAM and 2x 450MHz CPU's
                running Solaris 2.7 w/ latest Sun patches
        cache_mem 384 MB
        cache_dir /cache1 10000 48 256 ( Cache partitions are on )
        cache_dir /cache2 10000 48 256 ( separate hard drives, no )
                                                ( RAID. )

After building up about 15GB of cache (on disk), the performance now
looks
like this:

        Requests per day: ~1 million
        Uniq hosts per day: ~5000
        Cache hit rate: 49.1 %
        Avg transaction time - cache hit: 660 ms
        Avg transaction time - cache miss: 960 ms

With smaller cache_mem settings, the cache hit rate went down to about
42%,
and the avg transaction times for hits and misses went up to 900ms and
1000ms
respectively. I actually have two of these machines which I test out
different
settings on. So far, the line of diminishing return for me has been a
cache_mem
setting of 384MB. The response times may also be affected by the URL
filtering
software running on the machine, but that should affect both machines
equally.

Can you recommend any settings for this environment? With the default
cache_mem
setting at 16MB, the system responded very slowly (upwards of 1500ms
when it did
hit cache, vs about 1200 ms when it went direct), and the hit rate was
pretty
lousy (about 30%). If not, can you help me understand why I am getting
these
contrary results.

Thanks,
Jason

Dancer wrote:
>
> Marc-Adrian Napoli wrote:
> >
> > Dave,
> >
> > > > From: Marc-Adrian Napoli [SMTP:marcadrian@cia.com.au]
> > > >
> > > > cache_mem 500 MB
> > > >
> > > The normal reccomendation is to leave this at the
> > > default 8MB; what's your reasoning in using such
> > > a large value?
> >
> > 1GB of RAM.
> >
> > Is that a good enough reason? (honestly).
>
> Nope. Squid's memory cache is probably not as efficient as your
> filesystem's buffer-cache. For linux boxen, at least, I've narrowed the
> optimal size to between 5 and 15MB. Got to find time to narrow it
> further, if possible, and to check a few more kernels.
>
> D
Received on Thu Nov 11 1999 - 09:16:59 MST