From: Christoph Lameter
Date: Mon Aug 31 2009 - 11:41:09 EST

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.

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