On Mon, Sep 18, 2017 at 10:50 PM, Martin Polednik <mpoledni@redhat.com> wrote:
The hugepages are no longer a hook, but part of the code base. They
can be configured via engine property `hugepages`, where the value of
property is size of the pages in KiB (1048576 = 1G, 2048 = 2M).

Note that the question is about 4.1 and it doesn't seem like this change was backported to the 4.1 branch, right?
 
Specifying any other size not supported by the architecture (or just
"1") will use platform's default hugepage size.

I wonder if the end-to-end scenario, i.e., using the engine, of this ever worked.
This feature is broken on the master branch because of the switch to engine xml and is supposed to be fixed by [1]. However, while testing that fix I noticed that a check done by the scheduler [2] actually prevents us from setting a value that is not supported by the host.
Is this part really important?

[1] https://gerrit.ovirt.org/#/c/81860/
[2] https://github.com/oVirt/ovirt-engine/blob/master/backend/manager/modules/bll/src/main/java/org/ovirt/engine/core/bll/scheduling/policyunits/HugePagesFilterPolicyUnit.java#L56
 

On Mon, Sep 18, 2017 at 11:39 AM, Gianluca Cecchi
<gianluca.cecchi@gmail.com> wrote:
> Hello,
> I would like to go again in deep with what preliminary tested and already
> discussed here:
>
> http://lists.ovirt.org/pipermail/users/2017-April/081320.html
>
> I'm testing an oVirt node in 4.1.6-pre
>
> I don't find the vdsm hook for huge pages; doing a search I get these:
>
> vdsm-hook-ethtool-options.noarch : Allow setting custom ethtool options for
> vdsm controlled nics
> vdsm-hook-fcoe.noarch : Hook to enable FCoE support
> vdsm-hook-openstacknet.noarch : OpenStack Network vNICs support for VDSM
> vdsm-hook-vfio-mdev.noarch : Hook to enable mdev-capable devices.
> vdsm-hook-vhostmd.noarch : VDSM hook set for interaction with vhostmd
> vdsm-hook-vmfex-dev.noarch : VM-FEX vNIC support for VDSM
>
> Did anything change between 4.1.1 and 4.1.5/4.1.6?
>
> I'm making preliminary tests with an Oracle RDBMS and HammerDB in both a
> physical server and a "big" VM inside another same hw server configured with
> oVirt.
>
> Results are not bad, but I would like to see having huge pages inside the
> guest how could change results.
>
> Just for reference:
>
> The 2 Physical server are blades with each one:
> 2 sockets, each one with 14 cores and ht enabled, so in total 56
> computational threads
> 256Gb ram
> huge pages enabled
>
> VM configured with this virtual hw on one of them:
> 2 sockets, each one with 6 cores and ht so in total 24 computational threads
> 64Gb ram
> no huge pages at the moment
>
> Oracle SGA is 32Gb on both physical rdbms and virtual one.
>
> Thanks for any insight to test huge pages in guest
>
> Gianluca
>
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