[CentOS] CentOS 4.4 smp on Dual Quad Core Xeon

Mon Feb 26 22:52:46 UTC 2007
John Summerfield <debian at herakles.homelinux.org>

John R Pierce wrote:
> Morten Torstensen wrote:
>> Tru Huynh wrote:
>>> [tru at quadcore ~]$ uname -a
>>> Linux quadcore 2.6.9-42.0.3.ELsmp #1 SMP Fri Oct 6 06:28:26 CDT 2006 
>>> x86_64 x86_64 x86_64 GNU/Linux
>>> [tru at quadcore ~]$ grep -A4 processor /proc/cpuinfo
>>> processor       : 0
>>
>> Just take care with more than 8 CPUs, because you need the largesmp 
>> kernel then. Worked on a 8 socket, 16 CPU system where that was a pain 
>> due to binary kernel modules.
>>
>> Now those machines could be 32 CPU systems... and you could add 8 
>> sockets more. 64 CPUs on Intel platform with commodity hardware. Not 
>> that many years ago that would have been utopia :)
>>
> 
> 
> I believe those quad core Xeon "Clovertown" CPUs support hyperthreading 
> too.  which means 2 of them has 16 execution threads if you've enabled 
> hyperthreading in the BIOS.   While many people denigrate 
> hyperthreading, we've got some Java messaging/database/middleware stuff 
> that gets a HUGE boost on a older dual xeon* with HT enabled...  this is 
> with 2.8Ghz, 533Mhz FSB, 512K cache Xeons of this flavor:

I was astonished at the results of running this on an HT system:
#!/usr/bin/perl
#use integer;
$i = 0;
while ($i < 10000)
         {
                 $j = 0;
                 while ($j < 10000)
                         {
                                 ++$j;
                         }
                 ++$i;
         }

[summer at bilby ~]$


More precisely, two of them together:

time bin/bm.perl&time bin/bm.perl

I don't think anything written in Perl is very cache-friendly, but the 
HT system performed about as I'd expect dual-core to.




-- 

Cheers
John

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