[uml-devel] Re: The SKAS4 patch?? + ideas for 0 context-switch

[BlaisorBlade <blaisorblade_spam@yahoo.it>]

Alle 23:05, mercoledì 9 giugno 2004, BlaisorBlade ha scritto:

> > plus using segments will cost you a cycle or something
> > on every memory reference.
The Intel Manual 3 (Intel System Programming Guide - 253668 -15.pdf) says, at 
page 4-1 (page 107 in the PDF), that limit checking has no performance cost, 
and I expect this to hold especially for simply verifying if an address is 
below a limit. Maybe it could lie, ok, but maybe Alan Cox was referring to 
more complex segmentation tricks.

I'm also going to ask to Ingo Molnar (he sets a segment limit in the CS 
descriptor in his exec-shield patch, so he has probably benchmarked the 
result).
-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729




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