Re: [Bug 350] New: i386 context switch very slow compared to 2.4 due to wrmsr (performance)

From: Linus Torvalds (
Date: Wed Feb 12 2003 - 12:24:08 EST

In article <>,
Jamie Lokier <> wrote:
>I meant: the trampoline _stack_ lives in the TSS.
>There is no trampoline _code_.

Ahh, ok. That sounds quite doable, and all my complaints go away.

It still leaves the debug exception and NMI issue.

The debug exception case is easy to trigger: use gdb to single-step
through the user-lebel fast system call code, and you _will_ get a debug
exception on the very first kernel instruction (which is also the one
that doesn't have a valid stack).

So anybody want to actually try to implement this?

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