Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm

[Avi Kivity <avi@redhat.com>]

On 05/25/2010 07:21 PM, Anthony Liguori wrote:
> On 05/25/2010 11:16 AM, Avi Kivity wrote:
>> On 05/25/2010 06:01 PM, Anthony Liguori wrote:
>>> On 05/25/2010 10:00 AM, Avi Kivity wrote:
>>>> The latter.  Why is it less important?  If you don't inherit the 
>>>> memory, you can't access it.
>>>>
>>>>> You can also pass /dev/shm fd's via SCM_RIGHTs to establish shared 
>>>>> memory segments dynamically.
>>>>
>>>> Doesn't work for anonymous memory.
>>>
>>> What's wrong with /dev/shm memory?
>>
>> The kernel treats anonymous and nonymous memory differently for 
>> swapping (see /proc/sys/vm/swappiness); transparent hugepages won't 
>> work for /dev/shm (though it may be argued that that's a problem with 
>> thp); setup (/dev/shm defaults to half memory IIRC, we want 
>> mem+swap); different cgroup handling; somewhat clunky (a minor 
>> concern to be sure).
>
> Surely, with mmu notifiers, it wouldn't be that hard to share 
> anonymous memory via an fd though, no?

That's what I suggested with processfd().  I wouldn't call it easy but 
it's likely doable.  Whether it's mergable is a different issue.

-- 
error compiling committee.c: too many arguments to function