Re: [discuss] Re: [PATCH 1/3] Zone reclaim V3: main patch

[Andi Kleen]

On Thu, Dec 08, 2005 at 03:19:36PM -0800, Christoph Lameter wrote:
> On Thu, 8 Dec 2005, Andi Kleen wrote:
> 
> > I would use > LOCAL_DISTANCE or perhaps if you really want
> > a new constant with value 12-15. 
> 
> One may define RECLAIM_DISTANCE to be 12 for x86_64 in topology.h
> in order to get zone reclaim earlier for the opteron clusters. I would 
> think though that large opteron clusters also have distances > 20.
> 
> My experience is that at 20 systems do not need zone reclaim yet.

I really cannot confirm your experience here.

>  
> > > RECLAIM_DISTANCE can be set per arch if the default is not okay.
> > 
> > Well if anything it would be per system - perhaps need to make
> > it a boot option or somesuch later. 
> 
> The idea here was to avoid any manual configuration. The numa distances 

Sure as a default this makes sense.

I'm just questioning your default values.

> must related in some real way to performance (at least per arch) in order 
> for the automatic determination of zone reclaim to make sense. We could 
> have a boot time override but then RECLAIM_DISTANCE needs to be a 
> variable not a macro.

The macro can be always later defined to a variable, no problem.

-Andi

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