Question about Critical thresholds in Load-balancer plugin

jshiells

I tried searching the forum but fond no results for my query. If this has been asked and answered before please direct me to the thread.

my question is in rearguards to the "Critical thresholds" in XOA's Load-balancer (v0.9.1) plugin.

for the CPU % field, is that value based on 100% TIMES number of cores? or is it average load across all cores on a host, AND if it is 100% times number of cores is that TIMES 2 for virtual threads?

what setting below is correct:
1)Critical thresholds of 75% setting == average across all cores
2) 75% TIMES cores (44) = a setting of 3300% ?
3) 75% TIMES cores (44) TIMES 2 for HT = a setting of 6600%

Thanks

olivierlambert

Hi,

Ping @Bastien-Nollet

jshiells

@olivierlambert thanks

asking because i noticed when i had it set to 75% it was migrating VM's to different nodes in conditions i would consider premature. where the load on 44 core (88 thread) host was only at 8

Bastien Nollet

@jshiells this value is the average load across all cores on a host. To be more precise, it is a weighted average of the last 30min of this value. Migrations are triggered if this average exceeds 85% of the critical threshold defined in the plugin configuration, which is roughly 64% if you defined the critical threshold at 75%.

Other circumstances can trigger migrations :

if a host free memory is too close to critical threshold
anti-affinity rules
if you defined a performance plan behavior other than default (i.e. Preventive or vCPU balancing), migrations can be triggered even when at low memory and CPU usage

jshiells

@Bastien-Nollet Thank you, great explanation!