Re: Intel P6 vs P7 system call performance

Ulrich Drepper
2002-12-18T00:32:13Z

Linus Torvalds wrote:

> No, the way sysenter works, the table approach just sucks up dcache space
> (the kernel cannot know which sysenter is the one that the user uses
> anyway, so the jump table would have to just add back some index and we'd
> be back exactly where we started)
>
> I'll keep it the way it is now.

I won't argue since honestly, not doing it is much easier for me. But I
want to be sure I'm clear.

What I suggested is to have the first part of the global page be

.p2align 3
jmp sysenter_label
.p2align 3
jmp sysenter_label
...
.p2align
jmp userlevel_gettimeofday

sysenter_label:
the usual sysenter code

userlevel_gettimeofday:
whatever necessary

All this would be in the global page. There is only one sysenter call.

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