Re: [Xen-devel] Swiotlb

[Keir Fraser <keir@xxxxxxxxxxxxx>]

On 5/4/07 15:23, "Kieran Mansley" <kmansley@xxxxxxxxxxxxxx> wrote:

> While writing a driver for a device doing lots of DMA I've hit an
> "swiotlb_full()" problem.  This surprised me somewhat as I wouldn't have
> expected to need the use of the software TLB - it's a 64 bit capable
> device on a server with only 2 GB of RAM, and so I'd have expected to be
> using a hardware TLB.  Is this a peculiarity of Xen, or should I be
> right to be surprised?
> 
> I expect I can increase the size of the swiotlb to avoid this problem,
> but thought I'd check that there isn't something more fundamentally
> wrong first.

Well, I would agree that it sounds odd. You should definitely investigate --
you don't want to be invoking the swiotlb on the data path for a modern
high-speed device.

 -- Keir


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