Re: prezeroing V6 [2/3]: ScrubD

[Andrew Morton <akpm@osdl.org>]

Christoph Lameter <clameter@sgi.com> wrote:
>
> On Mon, 7 Feb 2005, Andrew Morton wrote:
> 
> > > No its a page fault benchmark. Dave Miller has done some kernel compiles
> > > and I have some benchmarks here that I never posted because they do not
> > > show any material change as far as I can see. I will be posting that soon
> > > when this is complete (also need to do the same for the atomic page fault
> > > ops and the prefaulting patch).
> >
> > OK, thanks.  That's important work.  After all, this patch is a performance
> > optimisation.
> 
> Well its a bit complicated due to the various configuration. UP, and then
> more and more processors. Plus the NUMA stuff and the standard benchmarks
> that are basically not suited for SMP tests make this a bit difficult.

The patch is supposed to speed the kernel up with at least some workloads. 
We 100% need to see testing results with some such workloads to verify that
the patch is desirable.

We also need to try to identify workloads whcih might experience a
regression and test them too.  It isn't very hard.

> > > memory node is bound to a set of cpus. This may be controlled by the
> > > NUMA node configuration. F.e. for nodes without cpus.
> >
> > kthread_bind() should be able to do this.  From a quick read it appears to
> > have shortcomings in this department (it expects to be bound to a single
> > CPU).
> 
> Sorry but I still do not get what the problem is? kscrubd does exactly
> what kswapd does and can be handled in the same way. It works fine here
> on various multi node configurations and correctly gets CPUs assigned.

We now have a standard API for starting, binding and stopping kernel
threads.  It's best to use it.