| Subject | Re: [PATCH 12/25] Remove a branch by assuming __GFP_HIGH == ALLOC_HIGH | From | Pekka Enberg <> | Date | Tue, 21 Apr 2009 10:46:22 +0300 |
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On Mon, 2009-04-20 at 23:19 +0100, Mel Gorman wrote: > Allocations that specify __GFP_HIGH get the ALLOC_HIGH flag. If these > flags are equal to each other, we can eliminate a branch. > > [akpm@linux-foundation.org: Suggested the hack]
Yikes!
> Signed-off-by: Mel Gorman <mel@csn.ul.ie> > --- > mm/page_alloc.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 51e1ded..b13fc29 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1639,8 +1639,8 @@ gfp_to_alloc_flags(gfp_t gfp_mask) > * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will > * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH). > */ > - if (gfp_mask & __GFP_HIGH) > - alloc_flags |= ALLOC_HIGH; > + VM_BUG_ON(__GFP_HIGH != ALLOC_HIGH); > + alloc_flags |= (gfp_mask & __GFP_HIGH);
Shouldn't you then also change ALLOC_HIGH to use __GFP_HIGH or at least add a comment somewhere?
> > if (!wait) { > alloc_flags |= ALLOC_HARDER;
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