Re: [RFC PATCH 0/5] futex: introduce an optimistic spinning futex

Mike Galbraith
2014-07-23T04:55:10Z

On Mon, 2014-07-21 at 09:42 -0700, Andi Kleen wrote:

> FWIW the main problem is currently that switch-through-idle is so
> slow. I think improving that would give a boost to far more
> situations.

Two high frequency idle enter/exit suckage spots:

1) nohz (tick) - it's expensive to start/stop tick on every micro-idle,
throttle it or something.

2) ondemand governor - tweak silly default settings to reflect the
reality that we routinely schedule communicating threads cross core.

(3. seek/destroy fastpath cycles, damn things multiply over time)

-Mike