Re: [PATCH] vmscan: skip freeing memory from zones with lots free

[Nick Piggin]

On Mon, Dec 08, 2008 at 03:25:10PM -0500, Rik van Riel wrote:
> KOSAKI Motohiro wrote:
> 
> >+	for (o = order; o < MAX_ORDER; o++) {
> >+		if (z->free_area[o].nr_free)
> >+			return 1;
> 
> Since page breakup and coalescing always manipulates .nr_free,
> I wonder if it would make sense to pack the nr_free variables
> in their own cache line(s), so we have fewer cache misses when
> going through zone_watermark_ok() ?

For order-0 allocations, they should not be touched at all. For
higher order allocations in performance critical paths, we should
try to fix those to use order-0 ;)

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