| Posted | Nick | Remark | |
|---|---|---|---|
| #openstack-nova - 2017-08-07 | |||
| 13:17:46 | jaypipes | cdent, bauzas: so, which bug to discuss first? | |
| 13:17:48 | bauzas | jaypipes: arf | |
| 13:18:03 | cdent | jaypipes of the two I mentioned, I think we’re done already | |
| 13:18:03 | bauzas | jaypipes: honestly, just the critical one bug | |
| 13:18:14 | cdent | 1st is fixed, 2nd is not immediately relevant | |
| 13:18:18 | bauzas | +1 | |
| 13:19:22 | cdent | the implication, however, of the 1st, matt’s comments about summing instead of maxing, and some of alex comments about evacuate, suggests we have a bit more work todo to nail it all down | |
| 13:19:25 | cdent | but progress is being made | |
| 13:20:49 | jaypipes | cdent: ya. | |
| 13:30:11 | edleafe | Scheduler subteam meeting in 30 minutes in #openstack-meeting-alt | |
| 13:30:23 | openstackgerrit | Balazs Gibizer proposed openstack/nova master: Raise NoValidHost if no allocation candidates https://review.openstack.org/491491 | |
| 13:31:26 | gibi | cdent, jaypipes, bauzas: my naive bugfix for the bug 1708637 | |
| 13:31:28 | openstack | bug 1708637 in OpenStack Compute (nova) "nova does not properly claim resources when server resized to a too big flavor" [High,In progress] https://launchpad.net/bugs/1708637 - Assigned to Balazs Gibizer (balazs-gibizer) | |
| 13:31:44 | gibi | cdent, jaypipes, bauzas: https://review.openstack.org/491491 | |
| 13:31:53 | bauzas | gibi: looking | |
| 13:34:27 | bauzas | gibi: unfortunately, that won't work | |
| 13:34:43 | bauzas | gibi: just one word : CachingScheduler (actually, two) | |
| 13:35:15 | bauzas | oh, fuck, nevermind | |
| 13:35:16 | gibi | bauzas: I might need more words than two to understand the reason | |
| 13:35:36 | bauzas | we're already under the USES_ALLOC_CANDIDATES conditional | |
| 13:35:53 | bauzas | gibi: CachingScheduler isn't using Placement | |
| 13:36:15 | bauzas | gibi: but on the other hand, it still runs the legacy filters | |
| 13:36:51 | bauzas | but like I said, we're under the conditional that asserts us that we already use placement | |
| 13:37:00 | gibi | OK, I think I see | |
| 13:37:21 | gibi | but then CoreFilter is still needed for the CachingScheduler. isn't it? | |
| 13:39:55 | bauzas | correct | |
| 13:40:05 | bauzas | well, if of course the operator wants it | |
| 13:40:15 | bauzas | any filter can be disabled | |
| 13:40:18 | gibi | sure | |
| 13:40:35 | gibi | it just mean an infinite overallocation on such resource | |
| 13:41:54 | openstackgerrit | Balazs Gibizer proposed openstack/nova master: Raise NoValidHost if no allocation candidates https://review.openstack.org/491491 | |
| 13:42:28 | jaypipes | gibi: did you run all the func tests for that patch? | |
| 13:42:38 | openstackgerrit | Balazs Gibizer proposed openstack/nova master: Raise NoValidHost if no allocation candidates https://review.openstack.org/491491 | |
| 13:44:03 | gibi | jaypipes: yes, I did and passed for me | |
| 13:44:15 | gibi | jaypipes: most of the functional tests using CachingScheduler as far as I know | |
| 13:44:31 | jaypipes | gibi: really? I don't think so... | |
| 13:46:04 | gibi | jaypipes: hm, my bad, it is the ChanceScheduler not the CacheScheduler | |
| 13:46:29 | gibi | s/CacheScheduler/CachingScheduler/ | |
| 13:46:30 | jaypipes | gibi: if that's the case, that's a very serious bug in our functional tests. | |
| 13:46:39 | cdent | the PlacementFixture was turned on functional test-wide recently | |
| 13:46:56 | gibi | jaypipes: I'm trying to find the place it is set... | |
| 13:46:56 | cdent | sorry, meant to add a ? on that ^ | |
| 13:47:01 | jaypipes | gibi: the ChanceScheduler is worthless. | |
| 13:49:42 | bauzas | jaypipes: people use chancescheduler for very simple functional tests involving the scheduler | |
| 13:49:54 | bauzas | only a very few use filterscheduler | |
| 13:51:58 | jaypipes | bauzas: since chance scheduler doesn't use placement, that's a mistake IMHO. | |
| 13:52:26 | jaypipes | we're not covering a large portion of our functional tests for no good reason. | |
| 13:53:22 | bauzas | jaypipes: if we run only one compute and want to boot one instance, why should we run filterscheduler and placement ? | |
| 13:53:22 | gibi | bauzas: do you know where the ChanceScheduler is set in the functional test env? | |
| 13:53:45 | bauzas | gibi: just look at self.flags(driver='chance_scheduler', group='scheduler') | |
| 13:53:45 | jaypipes | bauzas: because placement is now required. | |
| 13:54:34 | jaypipes | bauzas: we will never be able to get rid of the code in the compute node that does "claiming" if the chance scheduler is allowed to keep on existing. same for caching scheduler, frankly. | |
| 13:54:56 | gibi | bauzas: thanks. I always forget about the fact that it is chance_scheduler in the conf not ChanceScheduler | |
| 13:54:59 | bauzas | jaypipes: that's 2 different concerns IMHO | |
| 13:55:15 | bauzas | jaypipes: the main concerning one is that not all our drivers use placement | |
| 13:55:22 | bauzas | jaypipes: and that, I fully agree, should be fixed | |
| 13:55:41 | dansmith | we're going to fix that by deprecating caching scheduler | |
| 13:55:50 | bauzas | jaypipes: the second concern you express is that a large portion of our tests are not using filter_scheduler, but rather a dummy driver | |
| 13:55:50 | jaypipes | bauzas: no, I don't think the chance scheduler should be fixed at all. it should be removed. it does nothing at all. | |
| 13:56:01 | bauzas | jaypipes: that second concern is not a big deal to me | |
| 13:56:03 | dansmith | I dunno about chance scheduler, but I'd kinda expect the same | |
| 13:56:29 | jaypipes | bauzas: why is that second concern not a big deal to you? we're missing a huge % of coverage because of this. | |
| 13:56:37 | bauzas | dansmith: jaypipes: well, I personnally think that having different drivers is good for nova | |
| 13:56:52 | jaypipes | bauzas: yeah, I don't. | |
| 13:56:54 | bauzas | dansmith: jaypipes: and I expressed my idea of having the same input data for all drivers | |
| 13:57:12 | bauzas | just the scheduler algorithm should be different | |
| 13:57:27 | dansmith | having a completely ridiculous scheduler (chance) is not useful just to have an alternate option, IMHO | |
| 13:57:57 | bauzas | dansmith: well, I know some operators that use it :) | |
| 13:58:03 | dansmith | and the reason to have the cachingscheduler should go away when we're claiming in the scheduler, so... no real reason to keep tht either | |
| 13:58:14 | dansmith | bauzas: and? :) | |
| 13:58:27 | jaypipes | bauzas: the caching scheduler doesn't implement a different "algorithm". it implements a different storage mechanism and a different behaviour in responding to the instance update events. | |
| 13:58:44 | bauzas | I mean, filter scheduler being O(n2), some people tend to prefer other in-tree | |
| 13:59:09 | bauzas | jaypipes: I agree | |
| 13:59:53 | bauzas | jaypipes: let me rephrase, I just think that all drivers should by default get the list of hosts to verify by calling placement | |
| 13:59:56 | jaypipes | bauzas: what do you think the caching scheduler's big O notation is? | |
| 14:00:03 | bauzas | the same | |
| 14:00:07 | jaypipes | right. | |
| 14:00:15 | bauzas | but chance isn't | |
| 14:00:29 | jaypipes | chance doesn't do anything at all. | |
| 14:00:35 | edleafe | Scheduler subteam running now in #openstack-meeting-alt | |
| 14:00:43 | mriedem | o/ | |
| 14:00:48 | jaypipes | bauzas: it doesn't even consider if a compute has room for the workload. | |
| 14:00:58 | bauzas | jaypipes: it does ONE thing, picking a host | |
| 14:01:04 | bauzas | jaypipes: the rest is done by the compute claim | |
| 14:01:16 | bauzas | that's a quick scheduler at least | |
| 14:01:25 | bauzas | if you are enough spaced | |
| 14:01:26 | dansmith | heh | |
| 14:01:38 | jaypipes | bauzas: err, you and I have different ideas of efficiency I guess. | |
| 14:01:46 | bauzas | yeah, I know, it's orthogonal to what we do | |
| 14:02:03 | jaypipes | bauzas, dansmith: sched meeting in meeting-alt | |
| 14:02:03 | bauzas | I'm just describing *why* people use it | |
| 14:03:07 | dansmith | bauzas: can you find any reference to support your claim that some people use chance successfully and recommend it in anything other than toy environments? | |
| 14:03:31 | bauzas | dansmith: unfortunately, only hallways talks | |
| 14:03:39 | dansmith | the only such mention on the first page of google is a RAX presentation from 2013 that says "filter scheduler is the only legit one" | |
| 14:04:22 | bauzas | anyway, I'm not particularly attached to chance_scheduler | |
| 14:04:29 | bauzas | it's even broken if you use ironic | |
| 14:04:33 | stephenfin | cdent: https://review.openstack.org/#/c/490952/ is pretty much done, yeah. All that needs to be checked if if I've missed anything from the import process | |
| 14:04:59 | dansmith | bauzas: oh okay, seems like you're arguing to keep maintaining it | |
| 14:05:01 | bauzas | I'm just trying to explain that I want to make sure we keep a clear separation in between what placement gives to drivers, and how driver work | |
| 14:05:28 | bauzas | dansmith: sorry, I'm unclear, I'm just giving food for thoughts about why we have it in-tree | |