Re: RFC: THE OFFLINE SCHEDULER

Christoph Lameter
2009-08-31T15:41:02Z

On Fri, 28 Aug 2009, Thomas Gleixner wrote:

> > slab does run a timer every 2 second to age queues. If there was activity
> > then there can be a relatively long time in which we periodically throw
> > out portions of the cached data.
>
> Right, but why does that affect a CPU which is marked "I'm not
> involved in that game" ?

Its run unconditionally on every processor. System needs to scan through
all slabs and all queues to figure out if there is something to expire.

> > The device may periodically check for conditions that require action.
>
> Errm. The device is associated to some other CPU, so why would it
> require action on an isolated one ? Or are you talking about a device
> which is associated to that isolated CPU ?

Some devices now have per cpu threads. See f.e. Mellanox IB drivers. Maybe
there is a way to restrict that.