Re: [PATCH] change global zonelist order on NUMA v2

[KAMEZAWA Hiroyuki]

On Thu, 26 Apr 2007 11:47:44 +0200
Andi Kleen <ak@xxxxxxx> wrote:

> On Thursday 26 April 2007 11:34:17 KAMEZAWA Hiroyuki wrote:
> > 
> > Changelog from V1 -> V2
> > - sysctl name is changed to be relaxed_zone_order
> > - NORMAL->NORMAL->....->DMA->DMA->DMA order (new ordering) is now default.
> >   NORMAL->DMA->NORMAL->DMA order (old ordering) is optional.
> > - addes boot opttion to set relaxed_zone_order. ia64 is supported now.
> > - Added documentation
> > 
> > patch is against 2.6.21-rc7-mm2. tested on ia64 NUMA box. works well.
> 
> IMHO the change should be default (without any options) unless someone
> can come up with a good reason why not. On x86-64 it should be definitely
> default.
> 
> If there is a good reason on some architecture or machine a user option is also not a 
> good idea, but instead it should be set automatically by that architecture or machine
> on boot.
> 
Hmm...sounds reasonable. 

I have 2 idea for automatic way..

(1)Use new zonelist ordering always and move init_task's tied cpu to a
  cpu on the best node. 
  Child processes will start in good nodes even if Node 0 has small memory.

(2) Set Node's local highest zone to the top of zonelist.

I like (1). Does anyone have an idea ?

-Kame

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