On 6/25/14, 11:16 PM, Alfred Perlstein wrote:
On 6/25/14 5:41 AM, Attilio Rao wrote:
On Wed, Jun 25, 2014 at 2:09 PM, Gleb Smirnoff
<gleb...@freebsd.org> wrote:
On Wed, Jun 25, 2014 at 01:58:29PM +0200, Attilio Rao wrote:
A> > Log:
A> > xen/virtio: fix balloon drivers to not mark pages as WIRED
A> >
A> > Prevent the Xen and VirtIO balloon drivers from marking
pages as
A> > wired. This prevents them from increasing the system wired
page count,
A> > which can lead to mlock failing because of hitting the
limit in
A> > vm.max_wired.
A>
A> This change is conceptually wrong.
A> The pages balloon is allocating are unmanaged and they should
be wired
A> by definition. Alan and I are considering enforcing this
(mandatory
A> wired pages for unmanaged pages allocation) directly in the KPI.
A> This in practice just seem an artifact to deal with scarce wired
A> memory limit. I suggest that for the XEN case this limit gets
bumped
A> rather relying on similar type of hacks.
Proper limit would be to count pages wired by userland via mlock(2)
and enforce limit only on those pages. Pages wired by kernel should
be either unlimited or controled by a separate limit.
FWIW, I mostly agree with this. I think that the kernel and userland
limits should be split apart. But for the time being, rising the limit
is better.
Attilio
Can you explain? I would think that if you were designing some kind
of embedded device you would want to know exactly how much locked
pages there are overall, not just in userland.
Meaning you would not want to overcommit and have too many locked
pages due to kernel+user.
Perhaps that needs an API as well?
these pages are the VM equivalent of memory pages that were 'found to
be flaky and taken out of service"
I think "wired" is a bad description for those.
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