Re: Add prefetch switch stack hook in scheduler function

Keith Owens
2005-07-28T08:09:08Z

On Thu, 28 Jul 2005 09:41:18 +0200,
Ingo Molnar <mingo@elte.hu> wrote:
>
>* david mosberger <dmosberger@gmail.com> wrote:
>
>> Also, should this be called prefetch_stack() or perhaps even just
>> prefetch_task()? Not every architecture defines a switch_stack
>> structure.
>
>yeah. I'd too suggest to call it prefetch_stack(), and not make it a
>macro & hook but something defined on all arches, with for now only ia64
>having any real code in the inline function.
>
>i'm wondering, is the switch_stack at the same/similar place as
>next->thread_info? If yes then we could simply do a
>prefetch(next->thread_info).

No, they can be up to 30K apart. See include/asm-ia64/ptrace.h.
thread_info is at ~0xda0, depending on the config. The switch_stack
can be as high as 0x7bd0 in the kernel stack, depending on why the task
is sleeping.