Change in vdsm[master]: vm: migration: exponential downtime increment

danken at redhat.com danken at redhat.com
Tue Sep 9 10:55:19 UTC 2014


Dan Kenigsberg has posted comments on this change.

Change subject: vm: migration: exponential downtime increment
......................................................................


Patch Set 4: Code-Review-1

(3 comments)

http://gerrit.ovirt.org/#/c/25820/4//COMMIT_MSG
Commit Message:

Line 26: The rationale for this patch is to minimize the
Line 27: downtime of VMs pushing for low downtime values as much
Line 28: and as long as possible.
Line 29: This way, the downtime becomes more tightly related
Line 30: to the duration of the migration itself.
please explain better why waiting for 11 seconds after waiting for 10 seconds is not very smart.
Line 31: 
Line 32: Please note that this patch still preserve an linear
Line 33: increment of the wait time.
Line 34: 


http://gerrit.ovirt.org/#/c/25820/4/vdsm/virt/migration.py
File vdsm/virt/migration.py:

Line 365: 
Line 366:         delay_per_gib = config.getint('vars', 'migration_downtime_delay')
Line 367:         memSize = int(vm.conf['memSize'])
Line 368:         self._wait = (delay_per_gib * max(memSize, 2048) + 1023) / 1024
Line 369:         self._coeff = self._downtime ** (1 / float(self.DOWNTIME_STEPS))
_coeff -> _base
Line 370: 
Line 371:         self.daemon = True
Line 372:         self.start()
Line 373: 


Line 379: 
Line 380:             if self._stop.isSet():
Line 381:                 break
Line 382: 
Line 383:             downtime = int(self._coeff ** i)
make sure we don't begin with 0.
Line 384:             self._vm.log.debug('setting migration downtime to %d', downtime)
Line 385:             self._vm._dom.migrateSetMaxDowntime(downtime, 0)
Line 386: 
Line 387:         self._vm.log.debug('migration downtime thread exiting')


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Gerrit-MessageType: comment
Gerrit-Change-Id: I6401772f52ea28144452e67198bddff18f6703eb
Gerrit-PatchSet: 4
Gerrit-Project: vdsm
Gerrit-Branch: master
Gerrit-Owner: Francesco Romani <fromani at redhat.com>
Gerrit-Reviewer: Dan Kenigsberg <danken at redhat.com>
Gerrit-Reviewer: Francesco Romani <fromani at redhat.com>
Gerrit-Reviewer: Michal Skrivanek <michal.skrivanek at redhat.com>
Gerrit-Reviewer: Vinzenz Feenstra <vfeenstr at redhat.com>
Gerrit-Reviewer: automation at ovirt.org
Gerrit-Reviewer: oVirt Jenkins CI Server
Gerrit-HasComments: Yes


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