[libvirt] [PATCH 1/3] qemu: Move memory limit computation to a reusable function

[Paolo Bonzini]

Il 02/07/2013 13:40, Jiri Denemark ha scritto:
> On Tue, Jul 02, 2013 at 12:34:44 +0200, Paolo Bonzini wrote:
>> Il 02/07/2013 08:34, Jiri Denemark ha scritto:
>>> I'm not sure if that's
>>> the right think to do or not but it's certainly better than before when
>>> memory locking limit completely ignore the need for VRAM and per-disk
>>> cache. Unfortunately, the original formula was suggested by Avi, who
>>> moved to new challenges. Perhaps others could jump in and share their
>>> opinions (Paolo? :-P).
>>
>> I think the disk cache should not be counted in the memory locking
>> limit.
> 
> Hmm, I guess you're right. However, we're computing a limit and I feel
> like allowing QEMU to lock a bit more shouldn't make any bad effects or
> am I wrong? On the other hand, it would be pretty easy to let the
> function know what kind of limit it's going to compute each time it's
> called.

Yes, both ways are fine.  But you should at least have a comment.

>> Apart from that, the code you posted below makes sense.
> 
> Even with the 1GB addition for VFIO? I have to admit I'm a bit ignorant
> of VFIO but shouldn't that limit be derived from the number of attached
> devices

If that would be the amount of memory reserved for BARs (PCI memory
mapped regions), 1 GB should be enough.  Let's just ask Alex Williamson.

Paolo