Re: [Qemu-devel] [PATCH v2] Add option to mlock qemu and guest memory

[Satoru Moriya]

On 02/14/2013 03:39 PM, Michael Tokarev wrote:
> 15.02.2013 00:21, Satoru Moriya wrote:
>> We have some plans to migrate legacy enterprise systems which require 
>> low latency (10 msec order) to kvm virtualized environment. In our 
>> usecase, the system runs with other untrusted guests and so locking 
>> memory which is used by the system is needed to avoid latency impacts 
>> from other guests' memory activity.
> 
> Not a patch review, but maybe using (explicit) huge pages will solve 
> this issue already?  Huge pages aren't swappable...

For some scenarios, you're right.

But, I think, -mem-prealloc/-mem-path uses huge pages only for
guest RAM and it doesn't for qemu itself. It may cause latency impact.

Also using huge page reduces flexibility/usability because if
we do live migration, we have to allocate huge pages before
live migration (basically we don't use live migration for the
guest which needs low latency but sometimes we need to do it).

Regards,
Satoru