Re: [Xen-devel] [PATCH v6 11/16 RESEND] rbtree: optimize fetching of sibling node

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.11.17 at 16:20, <kpraveen.lkml@xxxxxxxxx> wrote:
> From: Michel Lespinasse <walken@xxxxxxxxxx>
> 
> When looking to fetch a node's sibling, we went through a sequence of:
> - check if node is the parent's left child
> - if it is, then fetch the parent's right child
> 
> This can be replaced with:
> - fetch the parent's right child as an assumed sibling
> - check that node is NOT the fetched child
> 
> This avoids fetching the parent's left child when node is actually
> that child. Saves a bit on code size, though it doesn't seem to make
> a large difference in speed.
> 
> Signed-off-by: Michel Lespinasse <walken@xxxxxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Cc: David Woodhouse <David.Woodhouse@xxxxxxxxx>
> Acked-by: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Cc: Daniel Santos <daniel.santos@xxxxxxxxx>
> Cc: Jens Axboe <axboe@xxxxxxxxx>
> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> [Linux commit 59633abf34e2f44b8e772a2c12a92132aa7c2220]
> 
> Ported to Xen.
> 
> Signed-off-by: Praveen Kumar <kpraveen.lkml@xxxxxxxxx>

Acked-by: Jan Beulich <jbeulich@xxxxxxxx>



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