Re: Intel P6 vs P7 system call performance

Linus Torvalds (torvalds@transmeta.com)
Tue, 17 Dec 2002 09:47:39 -0800 (PST)


On Tue, 17 Dec 2002, Richard B. Johnson wrote:
> On Mon, 16 Dec 2002, Linus Torvalds wrote:
> >
> > instruction for a system call just do a
> >
> > call 0xfffff000
>
> So you are going to do a system-call off a trap instead of an interrupt.

No no. The kernel maps a magic read-only page at 0xfffff000, and there's
no trap involved. The code at that address is kernel-generated for the CPU
in question, and it will do whatever is most convenient.

No traps. They're slow as hell.

Linus

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