400
Subj : Re: hyperthreading in database-benchmarks
To   : comp.arch,comp.programming.threads
From : Bill Todd
Date : Wed Oct 12 2005 07:37 pm

Oliver S. wrote:
> Has anyone found information on how much hyperthreading is able to 
> improve the
> performance of database-workloads (OTP as well as DWH)?

My recollection is that POWER5's SMT is said to give it something like a 
35% boost in TPC-C, and Montecito's coarser-grained 'hyperthreading' is 
said to provide less (more like 25%).  Those of course are both 
dual-thread SMT implementations without any more execution units than 
their non-SMT predecessors:  EV8's quad-thread implementation did (IIRC) 
contain more execution units, was fine-grained, and was said to provide 
over 2x (possibly as much as 3x - it's been a long time since I visited 
the material) the TPC-C throughput that a non-SMT version would have 
managed.

I don't recall where any of those numbers came from, though - so if you 
want sources, start Googling.

- bill

.

0