| Posted | Nick | Remark | |
|---|---|---|---|
| #openstack-nova - 2023-11-02 | |||
| 14:30:49 | bauzas | tbc, I've experienced a race condition | |
| 14:30:49 | sean-k-mooney | but i dont like the idea of us creating and deleting rps in genreal based on workload usage | |
| 14:31:09 | bauzas | since we update resource providers on a periodic | |
| 14:31:29 | bauzas | I was able to create 3 VMs (and allocate three VGPU allocations) | |
| 14:31:43 | bauzas | that's why I added the claim stuff | |
| 14:32:02 | bauzas | so, see, again, I'm not particularly attached to do this | |
| 14:32:19 | bauzas | if we go with statically defining which VFs are going to be used, fair | |
| 14:32:24 | sean-k-mooney | bauzas: we normally run the update avaiabel reosuces call elsewhere | |
| 14:32:32 | bauzas | I have checked | |
| 14:32:40 | sean-k-mooney | bauzas: we expcitly do it form the comptue manager in move claims | |
| 14:32:42 | bauzas | we do run the update *before* the spawn | |
| 14:32:53 | bauzas | not *after* :) | |
| 14:33:05 | dansmith | bauzas: agreed, deleting RPs as a result of allocation feels very wrong | |
| 14:33:26 | sean-k-mooney | dansmith: the only mitigation is we dont delete the mdev after the instance is moved/deleted | |
| 14:33:39 | sean-k-mooney | so provide the compute node is not restated | |
| 14:33:46 | sean-k-mooney | we will do the delete once | |
| 14:33:47 | dansmith | could we set reserved=total instead of deleting maybe? | |
| 14:33:57 | sean-k-mooney | but the extra RPs will get recated after a host reboot | |
| 14:34:15 | bauzas | dansmith: we would need to implement the reverse logic then | |
| 14:34:20 | sean-k-mooney | dansmith: reserved=total is what i was orgianlly thinking but the issue is total is going to 0 | |
| 14:34:26 | sean-k-mooney | and total cant be 0 | |
| 14:34:38 | sean-k-mooney | so we would need to do resrved=total=1 | |
| 14:34:47 | bauzas | and when to unreserve ? | |
| 14:34:57 | bauzas | say I delete my mdev ? | |
| 14:35:11 | bauzas | I'm a stubborn operator that deletes the mdevs, y'know | |
| 14:35:22 | sean-k-mooney | or you do a host reboot | |
| 14:35:39 | bauzas | honestly, I like the config approach | |
| 14:35:43 | sean-k-mooney | so ya the reserved=total approch is more complext then delete | |
| 14:35:56 | dansmith | sean-k-mooney: right I meant reserved=old_total | |
| 14:36:13 | bauzas | if you specific the max VGPUs per type, then we could do htis | |
| 14:36:34 | bauzas | I feel a disturbance in the force when I tell about deleting RPs | |
| 14:36:41 | sean-k-mooney | bauzas: its slightly more complex then that | |
| 14:37:33 | bauzas | I used the term "strawman", I think it was the right wording | |
| 14:37:36 | sean-k-mooney | max mdevs need nova to understand which phsyical deviec the mdevs are form | |
| 14:37:45 | bauzas | that is correct | |
| 14:37:52 | bauzas | we know the parent device | |
| 14:37:56 | bauzas | for a mdev | |
| 14:38:10 | bauzas | we already use this information to track | |
| 14:38:19 | bauzas | in nova today | |
| 14:38:33 | sean-k-mooney | well in the nvidia case the max mdev per type applies to the grandparent device | |
| 14:38:36 | bauzas | what we don't track *now* is to know the parent of a mdev capable device | |
| 14:38:59 | bauzas | and we can't rely on libvirt, it gives you the PCI-E root PCI address (I tested :) ) | |
| 14:40:19 | bauzas | sean-k-mooney: that's what libvirt is giving us https://paste.opendev.org/show/b3MHPT8VoIOBWw1tim2o/ | |
| 14:40:46 | bauzas | we know the parent addr tho | |
| 14:40:48 | bauzas | <capability type='phys_function'> <address domain='0x0000' bus='0x41' slot='0x00' function='0x0'/> | |
| 14:41:02 | sean-k-mooney | it tell you the part device | |
| 14:41:05 | bauzas | so you were right, we could use this | |
| 14:41:08 | sean-k-mooney | <parent>pci_0000_40_01_1</parent> | |
| 14:41:23 | bauzas | sean-k-mooney: no, you're wrong, that's not the PF address :) | |
| 14:42:01 | bauzas | [stack@lenovo-sr655-01 ~]$ lspci | grep 40:01.1 | |
| 14:42:01 | bauzas | 40:01.1 PCI bridge: Advanced Micro Devices, Inc. [AMD] Starship/Matisse GPP Bridge | |
| 14:42:01 | sean-k-mooney | ok can you give me access to that system so i can take a look | |
| 14:42:13 | bauzas | that's the PCI bridge address :) | |
| 14:42:45 | bauzas | but I told you, we have the parent PF address in the device XML | |
| 14:42:50 | sean-k-mooney | i orgianlly said we could get the info from sysfs because i knwo how to look it up there | |
| 14:43:09 | sean-k-mooney | we can get it form libvirt but i dont rememebr the element fo the top of my head | |
| 14:43:30 | sean-k-mooney | if we have it great | |
| 14:43:52 | sean-k-mooney | its <address domain='0x0000' bus='0x41' slot='0x00' function='0x0'/> | |
| 14:44:05 | sean-k-mooney | form the capability type='phys_function' YES | |
| 14:46:02 | bauzas | yeah, and thru sysfs, we have access to the physical function in /sys/class/mdev_bus/0000\:41\:00.4/physfn/ | |
| 14:46:06 | dansmith | okay done with my other meeting | |
| 14:46:18 | bauzas | but that's not a trivial change | |
| 14:46:29 | bauzas | we need to implement some libvirt config change | |
| 14:46:31 | sean-k-mooney | we can and should use the info form libvirt since its there | |
| 14:46:56 | sean-k-mooney | bauzas: we already have parsing logic for this in the pci tracker code in the libvirt driver | |
| 14:46:58 | bauzas | we already get information of the mdev capable devices thru libvirt | |
| 14:47:13 | bauzas | sean-k-mooney: oh you're right | |
| 14:47:28 | bauzas | dansmith: take time to digest | |
| 14:48:12 | bauzas | sounds less bugfix-y, more feature-y than my patch but I can do it | |
| 14:49:19 | bauzas | sean-k-mooney: fwiw, this is where we get information for a mdev cap device https://github.com/openstack/nova/blob/master/nova/virt/libvirt/driver.py#L8284 | |
| 14:49:22 | sean-k-mooney | bauzas: we should seperate the back protable fix form the final fix | |
| 14:49:48 | sean-k-mooney | bauzas: https://github.com/openstack/nova/blob/master/nova/virt/libvirt/host.py#L1321 is the functilalyt that extracts the pci info form te node dev | |
| 14:50:00 | bauzas | https://github.com/openstack/nova/blob/master/nova/virt/libvirt/driver.py#L8263 is where we get the capacity | |
| 14:50:10 | bauzas | so sounds easier than originally thought | |
| 14:50:13 | sean-k-mooney | https://github.com/openstack/nova/blob/master/nova/virt/libvirt/host.py#L1351-L1363 | |
| 14:50:21 | sean-k-mooney | that actully where we are parsing it | |
| 14:50:25 | dansmith | so max_mdevs_per_device works only because once you allocate one mdev type from a card, that card is locked into that type for the rest of the allocations right? | |
| 14:50:54 | bauzas | dansmith: you're correct, there is no heterogenous support | |
| 14:50:58 | artom | sean-k-mooney, we never updated the Neutron docs for the socket PCI NUMA affinity policy: https://docs.openstack.org/api-ref/network/v2/index.html#numa-affinity-policy | |
| 14:50:59 | sean-k-mooney | dansmith: in the simple case yes. but we also only support one mdev_type per card in nova | |
| 14:51:18 | bauzas | yup, there is no behavioural change in support | |
| 14:51:20 | sean-k-mooney | artom: we never updated the neutron extention for it | |
| 14:51:33 | sean-k-mooney | artom: its not a docs issue i belive we need an api change | |
| 14:51:40 | dansmith | sean-k-mooney: wait, is that the case even before we allocate? | |
| 14:51:41 | artom | sean-k-mooney, so we can't actually set it on the port at all? | |
| 14:52:06 | sean-k-mooney | dansmith: yes which means we break if tye allocate the wrong type manually | |
| 14:52:09 | bauzas | are we still talking of GPUs or PCI NUMA affinity now ? | |
| 14:52:13 | sean-k-mooney | dansmith: we have had customer do that | |
| 14:52:19 | artom | Anyways, I interrupted a convo with my dumb questions, carry on, I'll go look at the code | |
| 14:52:30 | sean-k-mooney | bauzas: im talkign to artom about something else | |
| 14:52:35 | artom | bauzas, ignore me and PCI policies | |
| 14:52:45 | bauzas | artom: no worries, we're reaching to some agreement soon I guess | |
| 14:53:04 | bauzas | dansmith: assigning a mdev type to a GPU is statically defined in nova | |
| 14:53:40 | sean-k-mooney | artom: https://github.com/openstack/neutron-lib/blob/master/neutron_lib/constants.py#L676-L681 | |
| 14:53:40 | dansmith | okay I'm confused | |
| 14:53:49 | dansmith | I thought ya'll said the opposite earlier | |
| 14:53:52 | bauzas | changing the value once you create mdevs is a breaking change that we don't support | |
| 14:53:57 | sean-k-mooney | artom: so the api will not accpet it and we are missing the osc support too | |
| 14:54:01 | dansmith | right I understand that part | |
| 14:54:18 | dansmith | are we going to gmeet? | |