On Mon, Mar 12, 2018 at 02:22:28PM +0100, Vlastimil Babka wrote: > On 03/01/2018 07:28 AM, Aaron Lu wrote: > > Matthew Wilcox found that all callers of free_pcppages_bulk() currently > > update pcp->count immediately after so it's natural to do it inside > > free_pcppages_bulk(). > > > > No functionality or performance change is expected from this patch. > > Well, it's N decrements instead of one decrement by N / assignment of > zero. But I assume the difference is negligible anyway, right?
Yes. > > > Suggested-by: Matthew Wilcox <[email protected]> > > Signed-off-by: Aaron Lu <[email protected]> > > Acked-by: Vlastimil Babka <[email protected]> Thanks! > > --- > > mm/page_alloc.c | 10 +++------- > > 1 file changed, 3 insertions(+), 7 deletions(-) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index cb416723538f..faa33eac1635 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1148,6 +1148,7 @@ static void free_pcppages_bulk(struct zone *zone, int > > count, > > page = list_last_entry(list, struct page, lru); > > /* must delete as __free_one_page list manipulates */ > > list_del(&page->lru); > > + pcp->count--; > > > > mt = get_pcppage_migratetype(page); > > /* MIGRATE_ISOLATE page should not go to pcplists */ > > @@ -2416,10 +2417,8 @@ void drain_zone_pages(struct zone *zone, struct > > per_cpu_pages *pcp) > > local_irq_save(flags); > > batch = READ_ONCE(pcp->batch); > > to_drain = min(pcp->count, batch); > > - if (to_drain > 0) { > > + if (to_drain > 0) > > free_pcppages_bulk(zone, to_drain, pcp); > > - pcp->count -= to_drain; > > - } > > local_irq_restore(flags); > > } > > #endif > > @@ -2441,10 +2440,8 @@ static void drain_pages_zone(unsigned int cpu, > > struct zone *zone) > > pset = per_cpu_ptr(zone->pageset, cpu); > > > > pcp = &pset->pcp; > > - if (pcp->count) { > > + if (pcp->count) > > free_pcppages_bulk(zone, pcp->count, pcp); > > - pcp->count = 0; > > - } > > local_irq_restore(flags); > > } > > > > @@ -2668,7 +2665,6 @@ static void free_unref_page_commit(struct page *page, > > unsigned long pfn) > > if (pcp->count >= pcp->high) { > > unsigned long batch = READ_ONCE(pcp->batch); > > free_pcppages_bulk(zone, batch, pcp); > > - pcp->count -= batch; > > } > > } > > > > >
