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Re: [Xen-devel] Memory allocation in NUMA system

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Memory allocation in NUMA system
From: "Yang, Xiaowei" <xiaowei.yang@xxxxxxxxx>
Date: Fri, 25 Jul 2008 15:51:38 +0800
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Keir Fraser wrote:
On 25/7/08 08:22, "Yang, Xiaowei" <xiaowei.yang@xxxxxxxxx> wrote:

>> 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.

How about by default we guarantee no more than 25% of a node's memory is
classed as 'DMA memory', and we reduce the DMA address width variable in Xen
to ensure that?

So, in your example, we would reduce dma_bitsize to 30.

 -- Keir


Yes, a good suggestion!

Thanks,
Xiaowei

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