Re: 2.7 thoughts

[William Lee Irwin III <wli@holomorphy.com>]

William Lee Irwin III wrote:
>> You need at least enough warning to get out of critical sections (e.g.
>> holding a spinlock) and dump registers out to memory. i.e. as long as it
>> takes to schedule out whatever's currently running on the thing.
>> ... and unless you want to start enforcing realtime bounds, the answer
>> to "how long do you have to give the kernel to do it?" is "forever".
>> In practice, it won't take forever, but no finite time is enforcible.

On Fri, Oct 10, 2003 at 04:12:31PM +0100, Jamie Lokier wrote:
> You can create a very peculiar scheduling state to make even
> spinlocked sections multi-task, so the CPU can be released in a finite
> time and quickly - about as quickly as taking an NMI and broadcasting
> the critical IPIs to tell other CPUs to take over.
> The peculiar state is restored to normal as soon as the number
> of concurrent critical sections no longer exceeds the number of real CPUs.

DOH. Okay, that would do it.


-- wli