Re: [PATCH RFC/RFB] x86_64, i386: interrupt dispatch changes

From: H. Peter Anvin
Date: Tue Nov 04 2008 - 16:37:16 EST


Ingo Molnar wrote:
> * Ingo Molnar <mingo@xxxxxxx> wrote:
>
>> And as hpa's comments point it out, compressing the rather stupid
>> irq stubs might be a third option that looks promising as well.
>
> ... and we should try and see how far we can compress those stubs,
> before we do any segment register based tricks.
>

Using the techniques previously mentioned, for 224 vectors:

1792 bytes ( 8 bytes/stub) - trivial.
1568 bytes ( 7 bytes/stub) - same without alignment.
952 bytes (~4 bytes/stub) - extra jump needed.

For comparison, the IDT itself is 2048 bytes on x86-32 and 4096 bytes on
x86-64.

-hpa
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