Re: [Xen-devel] [PATCH] fix memory allocation from NUMA node for VT-d.

[Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx>]

Hi Espen,

Your suggestion allocating memory from one of the nodes where the
IOMMU is attached improves performance more. But more memory is
needed, because structures are needed per IOMMU.

My patch keeps the current implementation, one Device Assignment
Structure and Address Translation Structure per guest.

Xen's user will assign a device to a closer guest. So, node of the
guest and node connected to IOMMU will be the same.
As a result, the memory performance will be improved with my patch.

Thanks,
--
Yuji Shimada

On Tue, 18 Nov 2008 12:00:37 +0000
Espen Skoglund <espen.skoglund@xxxxxxxxxxxxx> wrote:

> Given an FSB based system the IOMMUs sit in the north-bridge.  How
> does this work qith QPI?  Where in the system do the different IOMMUs
> sit?  Wouldn't it make more sense to allocate memory from one of the
> nodes where the IOMMU is attached?  Having the memory allocated from
> the node of the guest only helps when the guest needs to update its
> page tables.  I'd rather optimize for page table walks in the IOMMU.
> 
>       eSk


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