List:General Discussion« Previous MessageNext Message »
From:Rod Heyd Date:April 22 2009 8:49pm
Subject:Re: Mysql on Ultrasparc T2 and floating point performance
View as plain text  
On Wed, Apr 22, 2009 at 1:27 PM, Dan Nelson <dnelson@stripped> wrote:

> In the last episode (Apr 22), Rod Heyd said:
> > I've been running mysql on a T1000 (Ultrasparc T1) system for several
> > years now, and while I've been happy with the performance overall, the
> > poor floating point capability on these systems has been a
> disappointment.
> > Recently, I got my hands on a Sunfire T5420 system and I've been
> comparing
> > the floating point performance on this system with the T1000, and was
> > expecting to see a significant improvement in floating point by virtue of
> > the fact that the Ultrasparc T2 processor has 1 FPU per core as opposed
> to
> > 1 FPU per CPU.  However, I'm only seeing a marginal improvement for
> > floating point calculations, for example, a "select benchmark(100000000,
> > 1.0 + 2.0)" takes roughly 50 seconds to run on both of these systems,
> > however I was expecting a lot better performance from the T2 processor.
>
> If you are running just one command, then you are only using one of the 8
> FPUs on the T2.  Try comparing 8 parallel "select benchmark(100000000, 1.0
> +
> 2.0)" runs at once on each server.
>

Hi Dan,

Yes, actually, I already know that parallel performance will be much
improved, however, I was expecting more improvement on single threads as
well, since the specs say that it takes 40 clock cycles just to access the
FPU on the T1, but something like 6 clock cycles on the T2.  So just from
that perspective it seems like there should be a significant improvement for
single threads, not just parallel performance.  At least that's the way I
read the docs from Sun on this.  At any rate, my expectations here are
clearly wrong, and I guess I'd just like a better understanding of why I'm
getting it wrong.

Thanks,

Rod

Thread
Mysql on Ultrasparc T2 and floating point performanceRod Heyd22 Apr
  • Re: Mysql on Ultrasparc T2 and floating point performanceDan Nelson22 Apr
    • Re: Mysql on Ultrasparc T2 and floating point performanceRod Heyd22 Apr
      • Re: Mysql on Ultrasparc T2 and floating point performancemos22 Apr
        • Re: Mysql on Ultrasparc T2 and floating point performanceAndy Smith23 Apr