Messages in this thread | | | From | (Linus Torvalds) | Subject | Re: Hashing and directories | Date | 7 Mar 2001 10:21:56 -0800 |
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In article <003701c0a722$f6b02700$5517fea9@local>, Manfred Spraul <manfred@colorfullife.com> wrote: > >exec_mmap currenly avoids mm_alloc()/activate_mm()/mm_drop() for single >threaded apps, and that would become impossible. >I'm not sure how expensive these calls are.
They aren't that expensive: activate_mm() needs to flush the TLB, but we do that anyway in the re-use case too, so on the whole the expense is limited to having to do the extra allocation.
That expense might be at least partially offset by being able to do some things more simply - right now the mm re-use case actually has to be more careful than I really like for security and protection reasons, for example. We've had bugs in this area before - simplifying it would be nice. And it also gets rid of the special cases.
I don't think the patches to do this should be all that huge, but who knows? It's not a trivial part of the kernel.
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