-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 The scheduler in nova has a few filters (TypeAffinityFilter, SameHostFilter, DifferentHostFilter) that rely on information about the instances that already exist on a given host. Before Kilo, these filters made direct DB calls in order to make their decisions. This was changed in Kilo to have the HostManager pre-populate the host with its instances, either from an in-memory view in the scheduler, or, if that update option was turned off, by a single DB query per host per request.
A few days ago, Jim Rollenhagen noticed that this instance query was causing severe problems for an ironic installation. It was felt that such a query made no sense for ironic, as there would typically be a single 'host' for all ironic nodes, and that the query was returning hundreds of instances, none of which were needed. Our initial solution [1] was to simply disable instance queries in the IronicHostManager, as they were never needed, and were painful to execute. But subsequent discussion on IRC brought up some potential (although not very likely) use cases where this might not be true. One example was if there were two computes each talking to one of two ironic installations, one might use the SameHostFilter to ensure that a new ironic instance was placed in the same ironic environment as another instance. While this seemed possible, the idea of querying hundreds or thousands of instances to see if the target was in that group seemed like overkill. I suggested that if this were ever something that someone needed, creating a new filter would be a better way forward than trying to retrofit the virt design onto ironic. So we're looking for input on the wisdom of either approach, or ideas for a different approach. If you have experience with real-world ironic deployments, please share your insights. [1] https://review.openstack.org/#/c/206736/ - -- - -- Ed Leafe -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: GPGTools - https://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBCgAGBQJVu6MvAAoJEKMgtcocwZqLnusP/1D0xrT86mF+FUM/75gVGMlr xLD5DPRDBvLrrVIG7AqXAMAHx2pnVKuY5K5h6WLQkTItpvNTgv8MEDM8+Le+8EwA 42NCieQA0hzHULNzXwXRjLVBQ1BBUUtVuvTLslp7bUjsr9ftYfABaEeHA9uOPQmR Z1oadQAwDoUPF2LyVLCWuw2Fo27ewUKcHBeouLlCeVtE/k9FcLByf9q67Ffru7sZ TG9gI2UlWyUXSuijWJhzZPP1degEDC6+h774gSGdgsZVXk1+LGWfujg7iXcMZUr5 ZOWz3V8AjP3cWdTf38Hb2sjJEtskC8tCEDFfRiIZQCR3rSeJEfVTq0sglQWYuPSC x6PqVp1pzED/o6VDtluseoLBbKOjmnR6LL7X163W9L56LXntwXaCiwq8rrijt1/c 89KYkVVbltXJC71CR6RSB+7iM9T8CmaN7Usg9sTKv/yGFQw2D8eZJZ/iCIATIU03 ThRpyPFFNPdoFctwoIFlN4JDrjPq/kxd34yiK/50MqXbbiURpLbkMJloqGWBuOtP I9SAgK8tjAFr3dTJuZvBwzg/WOX4TBhwF91aoAizKnpyDU6Pw1FCTsLWEaAacsrU ko4V/Ntf7ATr6QzF/v2a7ZV7iqIFX+tKkK/jGu/kI8HxIDB+T2UXuVa+aERLPSyg wdg6BpK6ZS2GFd8Sj6bW =juot -----END PGP SIGNATURE----- __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: [email protected]?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
