During an OpenShift control plane scale test, while provisioning more than 64K load balancers ovn-controller stopped creating OF groups after it reached 65535 groups.

This artificial limit is defined in extend-table.h:

 
#define MAX_EXT_TABLE_ID 65535
 
OvS supports more groups/meters than that:
/* Last usable group number. */
OFPG_MAX = 0xffffff00,
 
/* Last usable meter. */
OFPM13_MAX = 0xffff0000,

Instead of the hardcoded 64K limit ovn-controller should use the real limits.

Symptoms:
At scale, when running out of group IDs, ovn-controller logs:

2023-10-02T14:05:44.497Z|00629|extend_table|ERR|65536 out of table ids.