----- Original Message -----
> On 09/26/2011 04:26 PM, Anthony Liguori wrote:
> > On 09/26/2011 03:19 PM, Dor Laor wrote:
> >> On 09/26/2011 11:01 PM, Adam Litke wrote:
> >>> Hi all,
> >>> I would like propose adding the Memory Overcommitment Manager
> >>> (MOM)
> >>> project to
> >>> oVirt. MOM is a daemon that is used to apply dynamic host-level
> >>> and
> >>> VM-level
> >>> tuning according to a customizable policy. Today MOM can control
> >>> memory
> >>> ballooning and KSM. Please see the following links for more
> >>> information:
> >>> Project wiki:
> >>> http://github.com/aglitke/mom/wiki
> >>> Source code:
> >>> git://github.com/aglitke/mom.git
> >>> KVM Forum presentation and video:
> >>> http://vimeo.com/15223652
> >>> developerWorks article:
> >>> In my view, MOM could be nicely integrated with oVirt-node and
> >>> VDSM.
> >>> I am
> >>> looking forward to your comments and am ready to address some
> >>> next
> >>> steps.
> >>> Thanks!
> >> +1 for mom, hope to see a dad too :)
> > Data Acceleration Director?
> > Joking aside, would MOM just be integrated directly into VDSM or
> > would
> > it remain as a separate project?
> > I can envision a world where MOM is just a feature of VDSM.
> The key question is how do we integrate it into the stack,
> - is it integrated into WDSM as Anthony mentions
> - or is a project that WDSM uses to provide MOM
> - etc.
First of all I think this is great! Thanks Adam!
Wrt the question above, the way I see vdsm going forward is a lot more policy
management, especially once we start talking about SLAs. This will involve a
lot more than just memory policies, and although I may be impartial here, I
think that this should fall under vdsm or under a policy engine project
(bigger scope than just memory) which vdsm would use. To elaborate, in
addition to memory, we need to manage policies around network, storage and cpu
and manipulate cgroups, tc, page cache etc. If we take page cache as an
example, it affects memory on the machine hence, MOM would like to tweak it
(also in the preso), but we already have recent results from the perf team to
change the defaults here to significantly increase I/O throughput, improve
fairness and reduce effect of buffered writers on VMs and we know that going
forward we'll have to tweak these parameters dynamically to adjust to varying
workloads, esp if we ever plan on making good the claim for a hybrid server.
Having separate projects tweaking the same params will not lead to good
Ayal, I definitely agree. I must admit that the project name MOM (while a nice
acronym), implies a restricted scope (memory only) but the architecture of MOM
does not limit its functionality to memory tuning only. I assert that MOM can
easily become the policy engine piece that you are speaking of.
The framework is very extensible (a set of Collectors that expose system state,
a set of Controllers that expose "tuning knobs", and a policy that reads
the state and manipulates the knobs. Adding control for cgroups is as simple as
writing a cgroups Collector and Controller.
Adam Litke <agl(a)us.ibm.com>
IBM Linux Technology Center