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SubjectRe: [PATCH v2] mm: per-thread vma caching
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)

Might do I suppose.

> + current->vmacache[idx] = newvma;
> +}
> --
> 1.8.1.4
>
>
>


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