Re: Linux 2.5 / 2.6 TODO (preliminary)

From: Maciej W. Rozycki (
Date: Fri Jun 02 2000 - 07:48:43 EST

On Fri, 2 Jun 2000, James Sutherland wrote:

> Provided the scheduler code respects the CPU affinity of processes, could
> you not just schedule a realtime idle loop, with hard affinity for the CPU
> in question? Better still, you could just "cli, hlt" on that CPU. Of
> course, you'll need to disarm the NMI watchdog, and have some way to wake
> up again. Skip the cli and just mask off all the IRQs except timer? Or can
> one CPU kick-start another like this?

 For Intel SMP you may just send an INIT IPI and this will shut the target
APIC and CPU down. You may also set up "cli; hlt" exit point from INIT to
catch some old 82489DX APIC based systems. The NMI input and watchdog
will be automatically disabled by the target APIC in both cases.

 The APIC architecture does also provide a way of waking up CPUs as we
already do on bootup.

+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+        e-mail:, PGP key available        +

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