Re: Memory allocation in NUMA system

["Yang, Xiaowei" <xiaowei.yang@intel.com>]

Keir Fraser wrote:
> On 25/7/08 04:34, "Yang, Xiaowei" <xiaowei.yang@intel.com> wrote:
> 
>  > Let's say we have a 2-node system, with node0 and node1's memory range
>  > being 0-0xc0000000 (<4G) and 0x100000000-0x1c0000000 (>4G) respectively.
>  > In that case, node1's memory is always preferred for domain memory
>  > allocation, no matter which node the created domain is pinned to. It
>  > results in performance penalty.
>  >
>  > One possible fix is to specify all range for the domain memory
>  > allocation, which means local memory is preferred. This change may be
>  > restricted only to the domain pinned to one node for less impact.
>  >
>  > One side effect is that the DMA memory size may be smaller, which makes
>  > device domain unhappy. This can be addressed by reserving node0 to be
>  > used lastly.
> 
> Doesn't your solution amount to what we already do, for the 2-node example?
> i.e., node0 would not be chosen until node1 is exhausted?
> 
Oh, what I mean is:
With the above possible fix, the domain memory is allocated from the 
node it pinned to. As node0's memory is precious for DMA, it's suggested 
to pin VMs to other nodes firstly.

And for non-pinned VM, we can stick to the original method.

Thanks,
Xiaowei