Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to3.6-rc5 on AMD chipsets - bisected

From: Alan Cox
Date: Sat Sep 15 2012 - 17:28:17 EST

> Yes, postgress performs loads better with it's spinlocks, but due to
> that, it necessarily _hates_ preemption. How the is the scheduler
> supposed to know that any specific userland task _really_ shouldn't be
> preempted at any specific time, else bad things follow?

You provide a shared page for a process group so it can write hints to
which is kernel mapped so the scheduler can peek..

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at