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SubjectRe: PATCH: Introduce struct vma_link_info
Em Fri, 20 Mar 2009 21:36:29 +0100
Peter Zijlstra <peterz@infradead.org> escreveu:

| On Fri, 2009-03-20 at 10:34 -0300, Luiz Fernando N. Capitulino wrote:
| > Andrew,
| >
| > Currently find_vma_prepare() and low-level VMA functions (eg. __vma_link())
| > require callers to provide three parameters to return/pass "link" information
| > (pprev, rb_link and rb_parent):
| >
| > static struct vm_area_struct *
| > find_vma_prepare(struct mm_struct *mm, unsigned long addr,
| > struct vm_area_struct **pprev, struct rb_node ***rb_link,
| > struct rb_node ** rb_parent);
| >
| > With this patch callers can pass a struct vma_link_info instead:
| >
| > static struct vm_area_struct *
| > find_vma_prepare(struct mm_struct *mm, unsigned long addr,
| > struct vma_link_info *link_info);
| >
| > The code gets simpler and it should be better because less variables
| > are pushed into the stack/registers. As shown by the following
| > kernel build test:
| >
| > kernel real user sys
| >
| > 2.6.29-rc8-vanilla 1136.64 1033.38 82.88
| > 2.6.29-rc8-linfo 1135.07 1032.44 82.92
| >
| > I have also ran hackbench, but I can't understand why its result
| > indicates a regression:
| >
| > kernel Avarage of three runs (25 processes groups)
| >
| > 2.6.29.rc8-vanilla 2.03
| > 2.6.29.rc8-linfo 2.12
| >
| > Rik has said to me that this could be inside error margin. So, I'm
| > submitting the patch for inclusion.
| >
| > Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
|
| I'd rather we look into using the threaded RB-tree to get rid of all
| this prev crap.

Okay, it makes sense. Also, Eduardo has a point for the hackbench's
regression: the patch is probably dropping some of gcc's optimizations
on the variables that got packed into the struct (although I haven't
checked the assembly yet).

So, better to forget this one.

Are there patches for the threaded tree available already?

--
Luiz Fernando N. Capitulino


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