Earlier  
Later
New Search
Posted Nick Remark
#openstack-nova - 2018-03-20
13:35:03 cdent Yeah, sure, not complaining, definitely want the brainstorming too
13:35:04 gibi efried: i mean I foresee a possible need of such trait based selection
13:35:18 cdent gibi: I think you missed _PLEASE on the end of that trait
13:36:49 jaypipes in any case, unfortunately, I now have a dentist appointment I need to get to... and then drop the dogs off at the spa and sit while my car gets serviced (will have my lappie for the last part, though, so will be online later)
13:37:12 efried enjay :)
13:37:49 sean-k-mooney[m] jaypipes: doggy spa days. you really do spoil them :)
13:40:40 gibi cdent: I think there is a limit about the lenght of a trait :)
13:40:45 cdent :)
13:41:21 gibi jaypipes: good luck with your errands
13:42:40 sean-k-mooney[m] gibi i belive its set in the db scema probaly 64,128 or256 charaters
13:43:44 sean-k-mooney[m] gibi: its 255 https://github.com/openstack/nova/blob/master/nova/db/sqlalchemy/api_migrations/migrate_repo/versions/041_resource_provider_traits.py#L43
13:44:24 sean-k-mooney[m] also aprently we set the charset to latin1 so no unicode traits. is that intentional ?
13:44:32 gibi sean-k-mooney[m]: OK, then I can fit the PLEASE at the end :)
13:45:54 gibi sean-k-mooney[m]: I think that is intentional https://github.com/openstack/nova/blob/f80b4e50093002f84b43ff245a605fbe44d34711/nova/api/openstack/placement/handlers/trait.py#L74
13:47:00 alex_xu_ jaypipes: For example, I want to a FPGA device with Funciton A, the request is 'resources=RC_FPGA_DEV:1&preferred=FPGA_FUNCTION_A'. Do you mean you only request one RC_FPGA_DEV, then weigh the RPs base on the summary of RPs in the response of allocation_candidates?
13:47:02 efried kaisers1: Responded. Note that I'm not saying any of those things will necessarily ever happen in this case. It's just one of those things that's good practice.
13:47:40 sean-k-mooney[m] ah of url parsing so we dont get sql injections... we still might get requests form people with non latin based alphabets at some point but i guess we can cross that bridge when we come to it
13:48:11 efried sean-k-mooney[m]: The schema only allows A-Z and _
13:48:14 efried and 0-9
13:48:35 sean-k-mooney[m] efried: the api schema yes i see that
13:48:50 alex_xu_ oh, jaypipes has a dentist appointment
13:50:47 gibi cdent: there is a debate about a need of microversion bump in https://review.openstack.org/#/c/502306/17/specs/rocky/approved/bandwidth-resource-provider.rst@142 this might be interesting to you as well
13:51:37 sean-k-mooney[m] efried: the api schema yes i see that
13:52:03 sean-k-mooney[m] ed ::
13:52:37 gibi cdent: you can free to forward the ping to other API experts :)
13:52:48 gibi s/can/are/
13:53:32 cdent gibi: hmmm. that is an interesting one. my general rule is capture well here: http://eavesdrop.openstack.org/meetings/nova_scheduler/2018/nova_scheduler.2018-03-19-14.00.log.html#l-178
13:53:53 alex_xu_ jaypipes: one more question, what is the reason you didn't want to add prefered trait in placement
13:54:25 sean-k-mooney[m] efried: damit lost the message. any TL:DR CUSTOM_SEÁNS_TRAIT would be invalid which is not much of a deal for me but some operators may want to create custom traits in there own language in teh future that said we should try to converge in a set of standard traits to cover there needs and cross the non english traits bridge when we really need too
13:56:29 efried alex_xu_: Because placement is a placer, not a weigher
13:57:10 efried alex_xu_: That's my interpretation of jaypipes' opinion, not necessarily my own
13:57:38 sean-k-mooney[m] alex_xu_: placement is fitting hard constratins, a prefereed trait is a best effort request. filtering based on a best effort request would potentially result in no valid host when there were hosts that met the required traits but no the prefered hence why jaypipes wanted to handel prefred in a weigher not in placement
13:58:13 sean-k-mooney[m] what efried said :)
13:58:50 gibi cdent: thanks, does this also means that in the old microversion we have to keep the old behavior which means not to fail the request just ignore the requested resources?
13:58:53 alex_xu_ efried: thanks for the high level explain, sean-k-mooney[m] thanks for the detail explain :)
13:59:03 efried heh
13:59:37 sean-k-mooney interesting. i have been testing out riot.im as an irc bouncer/bridge. looks like there is a 5-10 secodn delay when i use riot vs direct irc at least on posting. i get messages almost instanly on both
14:00:20 sean-k-mooney sean-k-mooney[m] is my riot.im client
14:00:21 cdent gibi: strictly speaking, yes, but it depends on the severity of the bad behavior
14:00:34 cdent I'm not generally a fan of the strict interpretation
14:02:23 gibi cdent: in this particular case the nova boot request was accepted and the requested resources was ignored. After the proposed change such a request would be rejected with an error message
14:02:27 alex_xu_ sean-k-mooney: Does that mean I require TRAIT_A, and prefer TRAIT_B, there is chance to return nothing when there is no TRAIT_B for any RP? not quite understand
14:02:59 cdent gibi: Again, using the strict interpretation, the older microversions should continue to accept
14:04:03 gibi cdent: assume for a second that we don't make it strict and allow failing in the old microversion. This would mean that there would be no difference between the old and the new microversion
14:04:34 gibi cdent: the only difference would be in the documentation
14:04:41 gibi cdent: about the meaning of the accpet
14:04:53 edleafe alex_xu_: "preferred" doesn't mean anything in placement, since it doesn't order anything
14:05:01 gibi cdent: in this case do we need the microversion bump just for the doc?
14:05:13 edleafe "required" implies a filtering, which is what placement does
14:05:54 alex_xu_ edleafe: 'preferred' order the number of traits which the RP has
14:07:15 cdent gibi: assuming that, then I wouldn't think a microverison was required for a doc change, because the behavior is the same everywhered, right? But if there is in fact a behavior change (in the API itself), that seems like a microversion, right?
14:08:11 alex_xu_ or you guys refer to the implement problem
14:09:45 edleafe alex_xu_: if I prefer a trait, I will accept an RP that doesn't have that trait if necessary. So Placement will return all RPs that satisfy the requirements. It is then up to the scheduler to sort them based on various things, and preferred traits would be one of those things
14:10:32 gibi cdent: I'm hesitant. The external behaviour will change as nova will reject a previously accepted the request. But even if nova today accept such request nova actually lies and nova does not fulfill the request properly as nova does not consider the QoS bandwidth policy on the port that is included in the request during the scheduling
14:11:21 gibi cdent: so by rejecting such request nova we clean up a lie
14:11:23 alex_xu_ edleafe: oh, the weigher will change the order again
14:11:29 cdent gibi: and you break working code
14:11:35 gibi cdent: true
14:11:59 cdent gibi: Which is what microversions are supposed to prevent, even though it means broken (in other ways) client code gets to continue existing
14:12:11 cdent I agree that it is a tricky problem and your hesitancy is warranted
14:12:23 cdent Do you feel the "lie" is a security problem?
14:13:05 gibi cdent: no, the lie is not a security issue. It is just a resource allocation issue
14:13:29 edleafe gibi: would you call the "lie" a bug?
14:13:39 edleafe IOW, Nova isn't doing what it's supposed to?
14:14:03 gibi edleafe: Nova missing support for including the port QoS policy in the placement decision
14:14:38 edleafe gibi: understood. What I'm asking is if nova not doing that is a bug
14:14:51 edleafe or is it just a feature that has not yet been implemented
14:15:01 gibi edleafe: it is a missing feature, not a bug.
14:15:09 gibi edleafe: it never worked before
14:15:15 edleafe gibi: ok, then it definitely needs a microversion
14:16:04 gibi edleafe, cdent: thank you for the discussion. I will link this discussion to the spec
14:16:26 mriedem onor it, but changed it to a 400 in the API in queens
14:16:26 mriedem gibi: "The external behaviour will change as nova will reject a previously accepted the request. But even if nova today accept such request nova actually lies and nova does not fulfill the request properly as nova does not consider the QoS bandwidth policy on the port that is included in the request during the scheduling" - same story with rebuilding a volume-backed instance with a new image; we used to accept that and just n
14:16:39 alex_xu_ each microversion discussion is a war
14:17:25 edleafe alex_xu_: https://twitter.com/EdLeafe/status/976100354650791936
14:17:40 mriedem not really
14:17:52 alex_xu_ edleafe: :)
14:18:42 gibi mriedem: so there is precedence not to bump microversion in this case even if it breaks client code
14:19:19 gibi edleafe, alex_xu_: :)
14:20:14 mriedem gibi: https://review.openstack.org/#/c/520660/
14:20:36 mriedem like most things, it's a case by case basis, but in the case of ^ we said it wasn't a microversion because it was a silent failure on the compute side
14:20:50 mriedem you shouldn't have to opt into being not broken
14:21:13 mriedem but i'm sure with enough time and examples we can spin that all ways
14:22:27 openstackgerrit Chris Dent proposed openstack/nova master: DNM: Demo code for microversion parse extraction https://review.openstack.org/550265
14:23:29 edleafe mriedem: yeah, that was why I was asking if it was a bug or a new feature. You shouldn't have to opt into bug fixes.
14:23:58 alex_xu_ mriedem: https://review.openstack.org/#/c/520660/ is a bug, I feel it is different
14:24:11 gibi mriedem, cdent, edleafe: in the bfv rebuild case that rebuild has never worked before
14:24:18 openstackgerrit Silvan Kaiser proposed openstack/nova master: Exec systemd-run with privileges in Quobyte driver https://review.openstack.org/554195
14:24:29 alex_xu_ gibi: the qos policy works with neutron currently, right?
14:25:05 gibi alex_xu_: the qos policy without placement support cannot really work properly even if neutron implemented some data plane enforcement for that policy
14:26:01 mriedem gibi: depends on what you mean by 'worked',
14:26:14 mriedem the api used to accept that kind of request and return a 202, and nothing would fail, but it was wrong
14:26:26 mriedem wrong in that it didn't actually replace the root disk
14:26:38 gibi alex_xu_: imagine that you promised 10G minimum bandwidth for two VMs on the same host and on the same 10G PF. That will cause inconsistency when both VM start using that minimum bandwidth heavily
14:26:53 mriedem today you can create a port with a qos policy and attach it to an instance, right? nova allows that w/o changing any resource consumption for that qos policy.
14:27:02 gibi mriedem: right
14:27:27 mriedem if we followed the volume-backed rebuild + new image path here,
14:27:41 mriedem we'd merge a patch to check if the port (or network) has a qos policy and fail if so
14:27:53 gibi yes
14:27:57 mriedem and then land a microversion that allows supporting those types of ports

Earlier   Later