On Mon, Mar 12, 2018 at 10:32:32AM -0700, Dave Hansen wrote: > On 03/09/2018 12:24 AM, Aaron Lu wrote: > > + /* > > + * We are going to put the page back to the global > > + * pool, prefetch its buddy to speed up later access > > + * under zone->lock. It is believed the overhead of > > + * an additional test and calculating buddy_pfn here > > + * can be offset by reduced memory latency later. To > > + * avoid excessive prefetching due to large count, only > > + * prefetch buddy for the last pcp->batch nr of pages. > > + */ > > + if (count > pcp->batch) > > + continue; > > + pfn = page_to_pfn(page); > > + buddy_pfn = __find_buddy_pfn(pfn, 0); > > + buddy = page + (buddy_pfn - pfn); > > + prefetch(buddy); > > FWIW, I think this needs to go into a helper function. Is that possible? I'll give it a try. > > There's too much logic happening here. Also, 'count' going from > batch_size->0 is totally non-obvious from the patch context. It makes > this hunk look totally wrong by itself.
