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#openstack-nova - 2017-04-21
14:22:03 smcginnis mriedem: That session is to discuss the track chair process and issues.
14:22:52 openstackgerrit sahid proposed openstack/nova master: network: update pci request spec to handle trusted tags https://review.openstack.org/458820
14:22:52 openstackgerrit sahid proposed openstack/nova master: libvirt: configure trust mode for vfs https://review.openstack.org/458514
14:22:53 openstackgerrit sahid proposed openstack/nova master: network: add command to configure trusted mode for VFs https://review.openstack.org/458513
14:24:22 mriedem smcginnis: what's a track chair?
14:24:28 mriedem those setting up the summit?
14:24:35 mriedem or those running a session?
14:24:52 openstackgerrit Alex Xu proposed openstack/python-novaclient master: Add `instance-uuid` flag to the migration-list https://review.openstack.org/458728
14:24:58 johnthetubaguy pick the sessions
14:25:03 mriedem alex_xu: you beat me to it
14:25:06 smcginnis mriedem: Decising which sessions to accept for the official schedule.
14:25:09 johnthetubaguy mriedem: done it twice, its a pain
14:25:15 mriedem oh, i don't care about that session then :)
14:25:17 smcginnis johnthetubaguy: Yep. :)
14:25:21 alex_xu mriedem: hope you didn't start that
14:25:29 mriedem alex_xu: no i didn't, thanks for doing it
14:25:34 alex_xu mriedem: np
14:29:16 mriedem alex_xu: comments inline :)
14:29:19 mriedem otherwise looks good
14:30:36 openstackgerrit Lee Yarwood proposed openstack/nova master: libvirt: Always disconnect_volume after rebase failures https://review.openstack.org/458807
14:31:37 mriedem bauwser: these https://review.openstack.org/#/c/457353/ https://review.openstack.org/#/c/448235/ https://review.openstack.org/#/c/458668/ https://review.openstack.org/#/c/456770/ https://review.openstack.org/#/c/448253/
14:31:52 bauwser mriedem: reviewy reviewy
14:32:03 mriedem ask and ye shall receieve
14:32:05 mriedem *receive
14:32:26 bauwser mriedem: FWIW, I haven't touched the scheduler claims spec since I need time to think about
14:32:51 mriedem i haven't either
14:32:52 bauwser about the super extra cool problem you showed to the world with overhead values
14:33:04 mriedem don't thank me, thank some performance tester internal to huawei
14:33:33 bauwser mriedem: FWIW, my honest first opinion is that problem it's something that we should leave out of placement
14:33:35 mriedem i didn't know the overhead stuff existed before that
14:33:58 bauwser mriedem: that looks something not really useful for placement and very related to the hypervisor
14:34:28 mriedem you have to solve it with placement one way or the other, either by tracking overhead in allocations, or forcing extra reserved inventory to make up for the overhead
14:34:29 bauwser so, say we leave in a world where we're not trying to eat all the resources but still have reserved room for that, then it's not a problem for placement
14:34:30 mriedem right?
14:34:52 mriedem i don't think we can punt on this
14:35:55 bauwser mriedem: if we have rescheduling, would it be a problem ?
14:36:14 bauwser we already don't place instances by reviewing that value
14:36:25 mriedem we reschedule based on it though
14:36:29 bauwser of course
14:36:31 mriedem but we don't have reschedules with super conductor
14:36:34 bauwser but how much ?
14:36:38 mriedem idk how much
14:36:47 bauwser so, it's rather a problem about how to reschedule
14:36:53 mriedem well,
14:36:59 mriedem the point of claims in the scheduler is you don't need to reschedule
14:37:17 bauwser honestly, I think claiming in the scheduler couldn't remove the compute node verifying the resources too
14:37:31 bauwser because sometimes, things can be wrong
14:37:57 bauwser so, having claims in the scheduler is cool but like Pareto (or more) fixing 95% of the number of problems we have
14:38:08 bauwser should we fix 5% of the current problems by adding more ?
14:38:15 bauwser if we still reschedule
14:38:18 mriedem if you can't reschedule from the compute, then what? NoValidHost and put the instance into ERROR state?
14:38:35 mriedem ^ was one of the options i proposed in the spec
14:38:44 bauwser anyway, since not all the resources are yet set in the placement API (like NUMA), we would still need to reschedule, right ?
14:38:54 mriedem i said account for the overhead by updating the allocations once on the compute, but people didn't like that b/c of quotas
14:39:19 bauwser because we use allocations for quotas, and I agree with the majority
14:39:42 bauwser so, either we say we add that for inventories *and not allocations*, or we say it's not a problem
14:39:54 bauwser and we leave reschedules fix that self-healing
14:40:07 mriedem we don't have reschedules
14:40:29 bauwser that's what I'm not sure we can just say it won't exist in a cellsv2 world
14:40:29 mriedem i thought the consensus the other day was pad the RP inventory reserved amount
14:40:37 mriedem via the get_inventory() method on drivers that calculate overhead
14:40:41 bauwser mriedem: I think the consensus looks good by me
14:40:53 mriedem reschedules are possible in a single-cell deployment
14:40:54 bauwser that's my "either" possibiltyu
14:41:05 mriedem but i don't think we should rely on them
14:41:09 bauwser okay
14:41:11 mriedem when designing things
14:41:34 mriedem dan proposed adding a config option to disable reschedules so you never have upcalls, regardless of deployment
14:41:44 bauwser so it leaves the idea to modify inventories to add more "something" for decrementing the "left" value
14:42:25 bauwser amending 'reserved' could be that "something" which wouldn't need to add a new DB fiedl
14:42:50 mriedem correct, that's what most people wanted the other day
14:42:58 bauwser mriedem: yup, and I +2d that change for the instance scheduler RPC call
14:43:06 mriedem it sucks for the operator because they have to configure reserved amounts,
14:43:13 mriedem unless we can come up with a scheme to automate it
14:43:14 bauwser mriedem: okay, if so, I think I can amend that spec
14:43:44 bauwser mriedem: I was rather thinking to have the inventory be modified by the RT to augment it by the sum of overhead for each instance
14:43:46 openstackgerrit Mikhail Feoktistov proposed openstack/nova master: Remove fstype param from ploop init https://review.openstack.org/444970
14:43:53 bauwser snap
14:44:01 bauwser to have the inventory.reserved value
14:44:02 cfriesen question...has nova ever considered setting the virtual disk logical/physical block size based on the host disk block size? currently the guest sees 512 even for disks with 4K block size, which potentially leads to extra read-modify-write overhead
14:44:40 leakypipes mriedem: k, on it.
14:46:23 bauwser leakypipes: mriedem: okay, I think then I have enough to amend the spec
14:46:44 leakypipes bauwser: coolio.
14:46:44 bauwser I'll try to provide a new rev' by today EOB or Monday
14:46:55 mriedem bauwser: so rather than add overheads to allocations, you want to add overhead to inventory.reserved during each build?
14:47:28 mriedem that could still get you in a 409 situation where we have to fail the build
14:47:31 bauwser leakypipes: do you agree with my idea to augment in the RT the reserved value given by the driver.get_inventory() method by the number of instance.overhead we have ?
14:48:19 mriedem we had talked about just a configurable value that get_inventory() would provide and isn't per-instance
14:48:47 figleaf I don't like treating reserved like an allocation - it should be set when the RP is created, and that's it
14:48:49 leakypipes bauwser: hmm, I must have missed that. lemme have another look at the spec
14:48:58 bauwser leakypipes: that's not yet in the spec
14:48:59 mriedem leakypipes: it's new as of bauwser today
14:49:02 leakypipes oh
14:49:05 mriedem last 5 minutes
14:49:13 figleaf it's sort of in my last comment on the spec
14:49:17 leakypipes no wonder I missed it then :)
14:49:22 bauwser I'm trying to explain that we find nodes based on what we ask vs. what we have as free
14:49:32 bauwser so, what we ask is the flavor
14:49:44 bauwser what we have is the inventory minus the allocations
14:49:48 leakypipes bauwser: sorry, lemme read back up. I just got back from breakfast :)

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