Re: kernel on an SMP system

From: P.T. Breuer (ptb_at_oboe.it.uc3m.es)
Date: 12/10/03 

Date: Wed, 10 Dec 2003 01:20:49 GMT

Brandon McCombs <bmccombs@ma.rr.com> wrote:
> Well from what I hear Windows 2000 is able to move the kernel off of the
> boot CPU and onto another CPU (not sure of the advantage) and I was just

The nature of smp code is that it can be running on any cpu at any time!
One would have to be somehow pinning the code on one cpu when it was in
the kernel to NOT have the kernel and user code always running
everywhere, if the cpus were started in the same code block.

You make it sound as though windows has a single kernel lock, like
linux had back in 2.0. More, you make it sound as though the kernel
code is only even started on one cpu.

> wondering if Linux could do the same thing. And from what I thought I
> knew of SMP systems, the jobs delegated by the kernel can run on all the
> CPUs but the kernel itself ran on just one.

At startup both cpus get pointed into the kernel code and from thereon
whatever happens happens! Both cpus can be in the kernel, or neither
can be, or one can be in and one out.

Peter

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