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#openstack-nova - 2023-04-25
16:24:16 bauzas sean-k-mooney: but we would still need to only set it if libvirt >=8
16:24:32 bauzas do we want to schedule on it, or is it just a performance fix ?
16:24:34 sean-k-mooney ya either only set it or preferable check this in init-host
16:24:43 sean-k-mooney and raise an error if you set the config option on an old libvirt
16:24:58 bauzas will there be any config knob ?
16:25:07 sean-k-mooney yes there shoudl be
16:25:12 ykarel yes that's second question
16:25:14 sean-k-mooney to set the cache size
16:25:15 ykarel Default setting for this new option, unconfigured or set to defaults like 32MB or 128 MB etc?
16:26:07 bauzas ykarel: if that's a config option, that indeed needs to be an hard fail if the operators sets this config value
16:26:18 bauzas and libvirt isn't recent enough
16:26:23 sean-k-mooney its not somethign we should hardcode
16:26:28 ykarel bauzas, sure will take care that in the patch
16:26:29 bauzas for that reason, I'm not happy with a default value except none
16:26:47 sean-k-mooney so it shoudl eb a config option im ok with a low default or leaving it unset
16:27:02 bauzas I'd prefer it unset for upgrade reasons
16:27:04 ykarel okk Thanks will keep it like that no default and let user configure it
16:27:05 sean-k-mooney bauzas: to your poitn it woudl be nice to have a triat for this but not required
16:27:28 bauzas ykarel: s/user/operator but I think I get your point
16:27:50 sean-k-mooney in this case really it will be the zuul job
16:27:50 ykarel so will propose the blueprint and update the patch with as per all the suggestions, Thanks
16:28:01 ykarel yes
16:28:03 sean-k-mooney this is of interest to peopel usign qemu for emulation
16:28:06 bauzas sean-k-mooney: man, we could recommend the operators to provide custom traits for this, exactly like vgpu types
16:28:36 bauzas I mean, eventually all the computes will support that, right?
16:28:44 sean-k-mooney yes
16:28:53 bauzas after a couple of releases, once we cap libvirt to >=8
16:29:10 sean-k-mooney so its not goign to break live migration
16:29:13 bauzas so I'm not a big fan of adding some scheduling thing for something that will eventually be supported mid-term
16:29:24 sean-k-mooney because we do not allwo live migration from a newer to older microversion
16:29:36 sean-k-mooney and for cold migration we will regenerate the xml on the approiate host
16:29:41 sean-k-mooney based on what it has avaiable
16:29:43 bauzas s/microversion/libvirt version but yeah
16:29:55 sean-k-mooney so i dont think we need anythign sepcial here
16:30:01 sean-k-mooney so ya custom trait woudl eb fine with me
16:30:13 sean-k-mooney they can use provider.yaml to set that if they want
16:30:17 bauzas cool, so that only seems a config knob to add, a check on init_host to fail if set and some magic in the driver to enable it
16:30:30 bauzas amirite ?
16:30:34 sean-k-mooney more or less
16:30:48 bauzas then, I'm OK for specless
16:30:56 sean-k-mooney +docs test ectra but its effectivly self contaied in the libvirt driver + the config tweak
16:30:58 bauzas we had precedents
16:31:11 bauzas + a relnote obviously
16:31:24 bauzas ykarel: do you agree with the direction ?
16:31:30 ykarel bauzas, yes
16:31:31 sean-k-mooney im ok with specless too assuming all of the above are done
16:31:41 bauzas anyone disagreeing ?
16:32:07 bauzas looks not
16:32:20 ykarel Thanks folks \o/
16:32:41 sean-k-mooney the only other thin i would suggest is once this is done a devstack patch shoudl be added to set this by default to say 32mb if qemu is used instead of kvm
16:33:37 sean-k-mooney thats out of scope fo this meeting and coud be doen on a per job basis too
16:33:39 bauzas #agreed enabling tb cache seems a specless blueprint, provided it only adds a config knob defaulting to unset, init_host failing on an older libvirt and just libvirt config tweak
16:34:01 bauzas #action ykarel to ping bauzas once the blueprint is created so that he can approve it
16:34:34 bauzas ykarel: and yeah, the scope of this feature can include devstack change and testing, for sure
16:34:53 bauzas like we could enable it in nova-next
16:35:41 sean-k-mooney bauzas: it will reduce the memory pressue in all our jobs so ocne we know it does not have a negitive impact we will proably want to have it enable din all of them
16:35:42 bauzas anything else to add on this item ?
16:35:55 sean-k-mooney but we can take it slow like the mariadb reduced memroy
16:36:00 bauzas sean-k-mooney: oh yeah, but I'd be in favor of testing it first
16:36:08 bauzas yah
16:36:33 bauzas ok, fwiw, I have another item
16:36:53 bauzas (bauzas) Can https://blueprints.launchpad.net/nova/+spec/cold-migrate-to-host-policy be specless ?
16:37:05 bauzas tl;dr: we discussed this at the PTG
16:37:29 sean-k-mooney assuming there is no change in the default policy then yes i think so
16:37:32 bauzas operators want a better granularity and maybe change the cold-migrate action to be admin_or_owner
16:37:46 bauzas but, here, we're just adding a new policy which is admin-only
16:37:55 bauzas so no API change, and no policy changes
16:38:11 bauzas it will just go check a separate policy if host is set
16:38:32 bauzas (literally a one-liner patch besides the policy file)
16:38:55 sean-k-mooney so basicaly there will be two poicies now for cold migration one for migratoin with a host adn one without but admin only by default
16:38:55 bauzas any objections to have it specless ?
16:39:01 sean-k-mooney and then operators can choose
16:39:18 sean-k-mooney +1
16:39:37 bauzas correct, like we have for os_compute_api:servers:create:forced_host
16:40:10 bauzas except I won't change the defaut rule for os_compute_api:os-migrate-server:migrate
16:40:34 bauzas both being admin-only
16:40:34 bauzas there will be os_compute_api:os-migrate-server:migrate and os_compute_api:os-migrate-server:migrate:host
16:40:48 bauzas (and operators can decide to open os_compute_api:os-migrate-server:migrate to endusers)
16:41:10 bauzas so I reiterate, any objection to have it specless ?
16:41:40 bauzas looks not
16:41:49 bauzas if so,
16:42:08 sean-k-mooney as long ast there is at least a blueprint im happy. i dislike changing policy without any tracker to works for me
16:42:17 bauzas #agreed https://blueprints.launchpad.net/nova/+spec/cold-migrate-to-host-policy accepted as a specless feature for Bobcat
16:42:31 bauzas sean-k-mooney: there is a blueprint, and there will be a relnote
16:42:45 bauzas and there will be functional tests covering this
16:42:53 sean-k-mooney yep all good.
16:43:15 bauzas I don't think we need a tempest change, do you think it's a nice to have ?
16:43:29 sean-k-mooney i dont think tempst shoudl test non default policy
16:43:41 bauzas yeah, that was my question
16:43:48 bauzas I'm not a QA expert
16:43:55 bauzas tempest is branchless
16:44:05 bauzas so that would be a bit hard to test it with tempest
16:44:22 sean-k-mooney i suspect you could reuse some fo the exsiting test with the right config if you needed too
16:44:24 bauzas anyway, I think we're done on this
16:44:44 bauzas about tempest, we could discuss this on the review time
16:44:50 bauzas thanks folks
16:44:51 opendevreview Artom Lifshitz proposed openstack/nova master: Save cell socket correctly when updating host NUMA topology https://review.opendev.org/c/openstack/nova/+/862964
16:44:51 opendevreview Artom Lifshitz proposed openstack/nova master: Reproduce bug 1995153 https://review.opendev.org/c/openstack/nova/+/862967
16:45:01 bauzas any other item to add before we end the meeting ?
16:45:22 auniyal small thing o/

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