Re: Memory v's CPU

From: Adam Neat <>
Date: Wed, 28 May 1997 12:38:31 +0000

> Hi,
> We are implementing a number of proxy servers at QUT. As we all
> know the common trade-off is between CPU and RAM, due to the dollars
> involved. I know we all want the best of both worlds, but in most cases
> it is not possible. :-)
> So the question remains, "What should we buy?? More memory( 512
> gig ) or bigger processor??? "
> All machines will be DEC Alpha's running Digital Unix OSF, there
> is no doubt about that. My impression is that we should go the memory
> option, what do you all reckon?? Is squid more of a memory hungry fellow
> or a processor intensive fellow???
> All my tests indicate "memory", am I right??
> Currently we have only one proxy in place, and it's a sorry sight.
> There is too much for it to handle now. We are going to start making
> everyone go through the proxy soon, and currently we are getting
> approximately 50,000 requests per hour. (we have no idea how many
> people are using the proxy ) so we expect that number to rise a lot.

We implemented a proxy server farm a month back and we opted for
Intel based achitecture after some testing.

We purchased 2 Intel based Pentium Pro 200 machines (ability to go
quad CPU if required) and 22Gb of SCSI disk.

We decided, via our tests, that more memory was better than CPU.

A test to try is this:

Plug a whopper of a CPU in (2 PPRO200's or 3 or 4) and only say 64Mb
of memory - try hitting the server. Now take out the >1 CPU's and
plug in 512Mb of memory. Watch it fly!

We noticed that although the machine was so overpowered for the job,
there was always this waiting period between when the user clicks on
OK/OPEN until the page actually starts to appear.

With 64M/32M we noticed a 1 - 4 second delay before the page arrived,
and with the 512Mb memory and 1 CPU, the page started to come even
before the Netscape Open Location dialoge box disappered.

I think squid (someone correct me if im wrong) cache's the location
of some "picture" of its cache contents in memory and if a location
or page is requested, it checks memory first - but if you have
limited amounts of core real memory, swapping to disk will take time.

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Received on Tue May 27 1997 - 19:40:08 MDT

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