What IO do you mean? Service in memory, postgres too, how simple sql query can be related to IO? I think it depends on the processor, but seriously, each of our servers have 10+K users. 48 per second is very low performance in this case. No packet loss and I talk about the server restart situation, so the server hasn't cache yet and 10+K users try to restore connection at the same time. And in this situation performance falls greatly. I would be happy if they entered one by one even at a speed of 48 per second. But they all enter together and instead of ten minutes it stretches out to ten hours. So - I need more auth threads.
On Thu, Feb 13, 2025 at 11:05 PM Marc <Marc@f1-outsourcing.eu> wrote:
it's definitely not postgres (and "one core" problem for postgres related with one heavy connect or data modifying, not for "select from")
I see only one process that uses CPU100% with a high amount of logins and it's auth. And I see only one 100% loaded core on the server.
It is because it is waiting for io I think. I just tried to test a bit on 1 thread and getting easily (as in stopped testing for more) 48 auths/s. dovecots auth is only 10% and slapd a little more. Maybe you have packet loss, maybe try enabling caching.