Re: Sybase on UltraSPARC IV

From: Casper H.S. Dik (Casper.Dik_at_Sun.COM)
Date: 09/29/04 

Date: 29 Sep 2004 09:03:48 GMT

>Per Eirik wrote:

>> I think CMT is comparable to Hyperthreading on Intel XEON CPUs. Sybase
>> recommends that Hyperthreading should be turned off to maximize Sybase
>> performance on Linux, see page 3:
>>
>> http://www.sybase.com/content/1025313/linux_optimizing_performance_wp.pdf
>>
>> Would that also be the case for UltraSPARC IV processors?

No, Hyperthreading and UltraSPARC IV CMT are not the same thing; the
UltraSPARC IV is two CPUs on a single die with some cache bits shared.
The performance is comparable to two independent CPUs.

Hyperthreading shares most of the CPU real estate; the maximum performance
gain is a few percentage points and a for certain workloads there's
a performance loss.

Casper 

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