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

[BlaisorBlade <bla...@ya...>]

Alle 23:05, mercoled=EC 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=20
page 4-1 (page 107 in the PDF), that limit checking has no performance cost=
,=20
and I expect this to hold especially for simply verifying if an address is=
=20
below a limit. Maybe it could lie, ok, but maybe Alan Cox was referring to=
=20
more complex segmentation tricks.

I'm also going to ask to Ingo Molnar (he sets a segment limit in the CS=20
descriptor in his exec-shield patch, so he has probably benchmarked the=20
result).
=2D-=20
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729