Re: [Xen-devel] [PATCH v3 1/5] xen: introduce two different max_nr_dom0/domU_grant_frames parameters

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 08/10/14 17:01, Stefano Stabellini wrote:
> On Wed, 8 Oct 2014, David Vrabel wrote:
>> On 08/10/14 14:00, Stefano Stabellini wrote:
>>> Remove max_nr_grant_frames, both variable and preprocessor symbol.
>>> Introduce two global variables max_nr_dom0_grant_frames and
>>> max_nr_domU_grant_frames, separately configurable via the Xen command line
>>> option "gnttab_max_nr_frames".
>>
>> Why?  I can't think of a sensible use case for this and you don't list
>> one.  dom0 doesn't really use grants so its current number grant frames
>> is usually 1 so it doesn't seem useful to restrict it differently.
> 
> See the recent discussion with Jan:
> 
> http://marc.info/?l=xen-devel&m=141260825209210

I still don't see a use case.  Either:

a) dom0 is the driver domain and doesn't need a large number of grants.

or

b) dom0 has a frontend driver, then the driver domain will have to scan
dom0's grant table thus dom0's grant table must be sized the same as domUs.

David


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