Looking for recommendations on tuning of nova-placement-api. I have a
few moderately-sized deployments (~200 nodes, ~4k instances), currently
on Ocata, and instance creation is getting very slow as they fill up.
I discovered that calls to placement seem to be taking a long time, and
even this is horribly slow:
$ time curl http://apihost:8778/
{"error": {"message": "The request you have made requires
authentication.", "code": 401, "title": "Unauthorized"}}
real 0m20.656s
user 0m0.003s
sys 0m0.001s
$
nova-placement-api is running under mod_wsgi with the "standard"(?)
config, i.e.:
...
WSGIProcessGroup nova-placement-api
WSGIApplicationGroup %{GLOBAL}
WSGIPassAuthorization On
WSGIDaemonProcess nova-placement-api processes=3 threads=1 user=nova
group=nova
WSGIScriptAlias / /usr/bin/nova-placement-api
...
Seems that the service is overwhelmed. Other WSGI services on the same
host are responding in a timely manner.
I'm thinking of bumping up "processes" quite a bit (maybe like 16 or
so). I'm assuming that increasing "threads" wouldn't help(?). Any
lessons from experience in this area?
Other suggestions? I'm looking at things like turning off
scheduler_tracks_instance_changes, since affinity scheduling is not
needed (at least so-far), but not sure that that will help with
placement load (seems like it might, though?)
TIA,
~iain
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