Michal Skrivanek has posted comments on this change.

Change subject: refine calculation of cpu topology
......................................................................


Patch Set 12:

(3 comments)

http://gerrit.ovirt.org/#/c/30896/12//COMMIT_MSG
Commit Message:

Line 13: ConfigValue.MaxNumOfSockets currently = 16
Line 14: maxVCpus            // ConfigValue.MaxNumberOfVmCpus
Line 15: smpThreadsPerCore   // optional - we don't send so defaults to 1
Line 16: 
Line 17: we need to send also
> why?
because the actual limit is per cluster level as defined in the engine. Till 
now we ignored the limit.
Line 18:  * MaxNumOfSockets
Line 19: 
Line 20:  the xml should be calculated like this
Line 21: 


Line 19: 
Line 20:  the xml should be calculated like this
Line 21: 
Line 22:   <vcpu current="smp">M</vcpu>
Line 23:   <topology cores="C" sockets="S" threads="T"/>
we need to change tha calculation to be within the qemu-kvm limits as defined 
in engine (currently we blindly send 160(from engine) and divide by C which can 
yield S>16, well, any time you use C<10)
Line 24: 
Line 25:   smp = smp
Line 26:   C   = smpCoresPerSocket
Line 27:   T   = cpuThreads


http://gerrit.ovirt.org/#/c/30896/12/vdsm/virt/vmxml.py
File vdsm/virt/vmxml.py:

Line 425:     def _calcTopology(self):
Line 426:         smp = int(self.conf.get('smp', '1'))
Line 427:         cores = int(self.conf.get('smpCoresPerSocket', '1'))
Line 428:         threads = int(self.conf.get('smpThreadsPerCore', '1'))
Line 429:         sockets = int(self.conf.get('maxNumberOfSockets', '16'))
> where does this 16 come from? Until this patch, we had maxVCpus=1 unless ot
it stays the same, if smp is not passed you get maxVCpus==1 at line 431

the new value is for max number of sockets only…we didn't have the limit and 
that's the bug this change is fixing..the de-facto limit qemu-kvm can do is 16 
sockets (but the actual supported one is per cluster level hence engine needs 
to send it).
Line 430:         maxVCpus = int(self.conf.get('maxVCpus', str(smp)))
Line 431:         maxVCpus = min(maxVCpus, (cores * sockets * threads))
Line 432: 
Line 433:         return {


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Gerrit-MessageType: comment
Gerrit-Change-Id: I0d71dfe98b67440c084b2a7bf8b292f6b9c3ae19
Gerrit-PatchSet: 12
Gerrit-Project: vdsm
Gerrit-Branch: master
Gerrit-Owner: Roy Golan <[email protected]>
Gerrit-Reviewer: Dan Kenigsberg <[email protected]>
Gerrit-Reviewer: Francesco Romani <[email protected]>
Gerrit-Reviewer: Michal Skrivanek <[email protected]>
Gerrit-Reviewer: Michal Skrivanek <[email protected]>
Gerrit-Reviewer: Omer Frenkel <[email protected]>
Gerrit-Reviewer: Roy Golan <[email protected]>
Gerrit-Reviewer: Saggi Mizrahi <[email protected]>
Gerrit-Reviewer: Yaniv Bronhaim <[email protected]>
Gerrit-Reviewer: Yeela Kaplan <[email protected]>
Gerrit-Reviewer: [email protected]
Gerrit-Reviewer: oVirt Jenkins CI Server
Gerrit-HasComments: Yes
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