Re: [PATCH 4/7] sched: implement force_cpus_allowed()

[Tejun Heo <tj@kernel.org>]

Hello,

On 12/08/2009 06:02 PM, Peter Zijlstra wrote:
> So its only needed in order to flush a workqueue from CPU_DOWN_PREPARE?
> And all you need it to place a new kthread on a !active cpu?

Yes, that's all I need.

> Or is this in order to allow migrate_live_tasks() to move the worker
> threads away from the dead cpu?

Nope, that's left to sched cpu callbacks.

> I'm really not thrilled by the whole fork-fest workqueue design.

Shared work pool kind of needs forks unless it's gonna create all the
workers upfront.  Most issues arise from corner cases - deadlocks, cpu
hotplugging, freeze/thaw and so on.  During usual operation, the
thread pool would remain largely stable.

Thanks.

-- 
tejun