lkml.org 
[lkml]   [2012]   [Aug]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v8 1/5] mm: introduce a common interface for balloon pages mobility
On Thu, Aug 23, 2012 at 07:25:05PM +0300, Michael S. Tsirkin wrote:
> On Thu, Aug 23, 2012 at 04:53:28PM +0300, Michael S. Tsirkin wrote:
> > Basically it was very simple: we assumed page->lru was never
> > touched for an allocated page, so it's safe to use it for
> > internal book-keeping by the driver.
> >
> > Now, this is not the case anymore, you add some logic in mm/ that might
> > or might not touch page->lru depending on things like reference count.
>
> Another thought: would the issue go away if balloon used
> page->private to link pages instead of LRU?
> mm core could keep a reference on page to avoid it
> being used while mm handles it (maybe it does already?).
>
I don't think so. That would be a lot more trikier and complex, IMHO.

> If we do this, will not the only change to balloon be to tell mm that it
> can use compaction for these pages when it allocates the page: using
> some GPF flag or a new API?
>

What about keep a conter at virtio_balloon structure on how much pages are
isolated from balloon's list and check it at leak time?
if the counter gets > 0 than we can safely put leak_balloon() to wait until
balloon page list gets completely refilled. I guess that is simple to get
accomplished and potentially addresses all your concerns on this issue.

Cheers!



\
 
 \ /
  Last update: 2012-08-24 00:01    [W:0.118 / U:1.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site