Re: kernel performance update - 2.6.14-rc3

[Sonny Rao <sonny@burdell.org>]

On Thu, Oct 06, 2005 at 11:36:47AM -0700, Chen, Kenneth W wrote:
> Nick Piggin wrote on Thursday, October 06, 2005 3:04 AM
> > Arjan van de Ven wrote:
> > >>dbench is catching some attention.  We just ran it with default
> > >>parameter.  I don't think default parameter is the right one to use
> > >>on some of our configurations.  For example, it shows +100% improvement
> > > 
> > > never ever consider dbench a serious benchmark; the thing is you can
> > > make dbench a lot better very easy; just make the kernel run one thread
> > > at a time until completion. dbench really gives very variable results,
> > > but it is not really possible to say if +100% or -100% is an improvement
> > > or a degredation for real life. So please just don't run it, or at least
> > > don't interpret the results in a "higher is better" way.
> > > 
> > 
> > As a disk IO performance benchmark you are absolutely right.
> > 
> > Some people like using it to test VM scalability and throughput
> > if it is being used on tmpfs. In that case the results are
> > generally more stable.
> 
> Thank you for the suggestion, we will look into the options.  I agree here
> as well, and I also don't consider dbench as a serious disk I/O performance
> benchmark.  There are other workloads that we ran (IOzone, aiostress, and my
> favorite "industry standard database workload") which covers disk I/O side
> pretty well.

Also, make sure you are running dbench version 3, it has much much
better reproducibility and self-consistency than version 2.

Sonny