Re: [ckrm-tech] [PATCH 4/7] UBC: syscalls (user interface)

Andi Kleen
2006-08-21T09:04:15Z

On Monday 21 August 2006 10:42, Magnus Damm wrote:

> No problem. The second URL pointed to a x86_64 version where I tried to
> break out code to make some kind of generic NUMA emulation layer. At
> that time no one seemed interested in that strategy as a simple resource
> control solution so I gave that up.
>
> For x86_64 I think it's only worth mucking around with the code if
> people believe that it is the right way to go for in-kernel resource
> control.

Does it by chance fix the existing code? Andrew has been complaining
(and I could reproduce) that numa=fake=16 makes it triple fault at boot.
The theory was that it didn't like empty nodes which can happen this way.
I unfortunately didn't have time to look into it closely so far.

> The x86_64 patches above include code to divide each real NUMA node into
> several smaller emulated nodes, but that is kind of pointless if people
> only use it for non-resource control purposes, ie just to play with
> CPUSETS and NUMA on non-NUMA hardware. For simple purposes like that I
> think the existing NUMA emulation code for x86_64 works perfectly well.
>
> I still think that i386 users would benefit from NUMA emulation though.
> If you want me to up-port the i386-specific code just let me know.

I personally have my doubts about 32bit NUMA -- it will always have
ZONE_NORMAL only on a single node, which limits it very much.
But ok I guess it might be useful to somebody.

-Andi