Re: [Xen-devel] Xen 4.0.1 "xc_map_foreign_batch: mmap failed: Cannot allocate memory"

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 05.01.11 at 18:48, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
wrote:
> On Wed, 5 Jan 2011, Jan Beulich wrote:
>> But this means it can have very close to the total amount of
>> memory the guest has in flight on its own. Clearly this should
>> be throttled based on available memory (just consider you have
>> multiple such I/O hungry guests).
> 
> This is true in theory, but Qemu emulates a PIIX3 chipset that only has
> two dma engines so I don't believe is possible to have more than 2 dma
> requests in flight.
> However I am not sure what is the maximum size for a single dma request.

Oh, no, we're talking about guests using pv drivers (I thought that
was said in the original mail).

Jan


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