Re: Design question for PV superpage support

[Mick Jordan <Mick.Jordan@sun.com>]

On 03/02/09 08:43, Mick Jordan wrote:
> On 03/02/09 05:54, Dave McCracken wrote:
>> The solution I am working on for how to support Linux hugepages (Xen 
>> superpages) involves creating domains made up entirely of 
>> superpages.  I can create a working domain with superpages and am in 
>> the process of supporting it in save/restore.
>>
>>   
I'm assuming that this means that everything is upgraded from 4K to 2MB. 
E.g. pfn 0 = 0, pfn 1 = 2MB., etc., and the mfn<->pfn maps also.
> This wouldn't work too well for me in the case of thread stacks 
> because we need to map out parts of the stack and, although we want 
> large virtual stacks, we don't want do dedicate that much physical 
> memory. Is it really difficult to support mixed pages sizes in the 
> general case, e.g., save/restore etc.?
Save/restore is definitely important for me and we do support it at 
present. I'm wondering if I might be able to "reapply" my 2MB mappings 
after a restore on a 4K system, given that these are just layered on a 
1-1 mapping between physical/virtual for all allocated memory.

Mick