Re: 2.4: why is NR_GFPINDEX so large?

Jamie Lokier
2000-06-22T19:51:29Z

Andrea Arcangeli wrote:
> >So I suppose the best way to optimize this is to make sure that
> >"NR_GFPINDEX * sizeof(zonelist_t)" is a multiple of the cache line size?
>
> Yes but only in SMP. On an UP compile you can save space. For this purpose
> in ac22-class there's a ____cacheline_aligned_in_smp macro that you can
> use for things like that (it relies on the compiler enterely).

Does ____cacheline_aligned_in_smp guarantee the _size_ of the object is
aligned, or merely its address?

You can always make an array of one element containing an aligned object
I suppose.

Longer term some variation of the per-CPU data area patch should be used.
If only it can be made nice :-)

-- jamie