On Tue, 2014-02-25 at 19:35 +0100, Peter Zijlstra wrote:
> On Tue, Feb 25, 2014 at 10:16:46AM -0800, Davidlohr Bueso wrote:
> > +void vmacache_update(struct mm_struct *mm, unsigned long addr,
> > + struct vm_area_struct *newvma)
> > +{
> > + /*
> > + * Hash based on the page number. Provides a good
> > + * hit rate for workloads with good locality and
> > + * those with random accesses as well.
> > + */
> > + int idx = (addr >> PAGE_SHIFT) & 3;
>
> % VMACACHE_SIZE
>
> perhaps? GCC should turn that into a mask for all sensible values I
> would think.
>
> Barring that I think something like:
>
> #define VMACACHE_BITS 2
> #define VMACACHE_SIZE (1U << VMACACHE_BITS)
> #define VMACACHE_MASK (VMACACHE_SIZE - 1)
Hmm all that seems like an overkill.
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