Re: [Xen-devel] [PATCH] Add 2M page support to Xen balloon driver

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> Dave McCracken <dcm@xxxxxxxx> 16.06.09 17:53 >>>
>
>This patch adds a kernel command line option "balloon_hugepages" that, when 
>enabled, will make the balloon driver work in 2M pages (ie hugepages).  This 
>will work in conjunction with the "superpages" domain creation option so once 
>a domain is created with 2M contiguous pages it will continue to free and re-
>allocate at the 2M page size.
>
>Note that the current hypervisor code does not allow 2M page allocations for 
>all guest domains.  Keir has agreed to change the hypervisor to allow them, 
>but for now "balloon_hugepages" should only be specified on hypervisors that 
>have this change.

How would that work with future (currently only some piece of dead code in
xen-netfront.c does so) code altering the p2m map outside of the balloon
driver? Shouldn't you at least verify the large page you allocated is indeed
machine-contiguous?

Also, after reasonably long uptime and on a reasonably loaded machine -
how good are the chances you would be able to allocate a large page
through alloc_pages() in the first place?

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel