Author: W B Hacker Date: To: exim users Subject: Re: [exim] Fastest Exim server ever
Marc Perkel wrote: >
> W B Hacker wrote:
>> Marc Perkel wrote:
>>
>>
>>> Yes - we will go wide if need be using multiple servers in parallel.
>>> Going to start with an Intel Quad core and 8 gigs of ram.
>>>
>> Only if you buy the top-end Xeon and MB 'glue' that can *use* over 4GB.
>> Remember, Intel 'commodity' CPU only have 64-bit *extensions*.
>>
>> NIC's and storage controllers don't DMA into the voltage regulator
>> chipsets - they need RAM and address space.
>>
>> For affordable Core-2 Quad, calculate as:
>>
>> (4 GB minus reserves for VGA and bus denizens)
>>
>> - e.g about 3 1/4 GB with decent VGA, 3 3/4 GB if headless.
>>
>> Any more RAM wanted, you'll be better off with AMD-64, UltraSparc, HPPA
>> (PA-RISC/Itanium), Power5/6, roughly in order of increasing cost.
>>
>> And it isn't just the architecture - the 'commodity' OS'en most of us
>> here use don't all handle the above-4GB RAM as fast as the below-4GB RAM.
>>
>>
>
> So Bill, are you saying then that I should get an AMD CPU? I personally
> run dual core AMD with 8 gigs of ram and the 64 bit version of Fedora
> and I can use the full 8 gigs. Are you saying the Intel chips don't do that?
>
>
I'm saying they don't do it *well*.
First, there is a 'gap' between say 3.5 and 4+ GB.
Second, the 'extension' require extra CPU cycles to get at the larger
RAM (over 4 GB).
Contrast that with even a similarly-priced, but older-fab AMD.
Look also at dual, quad, and 8-socket MB from Tyan and Serverworks.
Note the separate memory banks for AMD, shared ones for Intel.
Note also that Intel MB are being pushed to DDR 800, 1033 - and faster,
while AMD is able to deliver comparable performance with cheaper DDR2
533 & 667.
- back to the original issue:
Take two similar - even identical servers - no need that they (yet) be
top-end gear - old ones pulled last year will do.
Put them on an internal (only) LAN.
Configure them identically, and so that any message from one to the
other gets sent back - i.e. you WANT a 'loop'.
Inject a message, and watch the traffic grow until it hits a resource
bound (could be queue, could be link, probably WON'T be CPU - not at
first, anyway).
My guess is you will max-out at well under a million messages a day.
About 12 per second. Or less.
For 50,000 per second, 4,096 boxes might do the job... or more..
IF you could get the bandwidth, the HVAC, and the power they need.
