On Tue, Jan 25, 2011 at 9:31 AM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> struct mmu_gather {
> struct mm_struct *mm;
> unsigned int nr; /* == ~0U => fast mode */
> + unsigned int max;
> unsigned char fullmm; /* non-zero means full mm flush */
> unsigned char need_flush; /* really unmapped some PTEs? */
> unsigned long start_addr;
> unsigned long end_addr;
> - struct page *pages[FREE_PTE_NR];
> + struct page **pages;
> + struct page *local[8];
> };
Overall it looks OK - builds, boots & runs too. One question about
the above bit ... why "8" elements in the local[] array? This ought to be
a #define, maybe with a comment explaining the significance. It doesn't
seem to fill out struct mmu_gather to some "nice" size. I can't think
of why batching 8 at a time (in the fallback cannot allocate **pages case)
is a good number. So is there some science to the choice, or did you
pluck 8 out of the air?
Thanks
-Tony
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