On February 16, 2017 4:11 PM Mel Gorman wrote:
> On Thu, Feb 16, 2017 at 02:23:08PM +0800, Hillf Danton wrote:
> > On February 15, 2017 5:23 PM Mel Gorman wrote:
> > > */
> > > static int kswapd(void *p)
> > > {
> > > - unsigned int alloc_order, reclaim_order, classzone_idx;
> > > + unsigned int alloc_order, reclaim_order;
> > > + unsigned int classzone_idx = MAX_NR_ZONES - 1;
> > > pg_data_t *pgdat = (pg_data_t*)p;
> > > struct task_struct *tsk = current;
> > >
> > > @@ -3447,20 +3466,23 @@ static int kswapd(void *p)
> > > tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
> > > set_freezable();
> > >
> > > - pgdat->kswapd_order = alloc_order = reclaim_order = 0;
> > > - pgdat->kswapd_classzone_idx = classzone_idx = 0;
> > > + pgdat->kswapd_order = 0;
> > > + pgdat->kswapd_classzone_idx = MAX_NR_ZONES;
> > > for ( ; ; ) {
> > > bool ret;
> > >
> > > + alloc_order = reclaim_order = pgdat->kswapd_order;
> > > + classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx);
> > > +
> > > kswapd_try_sleep:
> > > kswapd_try_to_sleep(pgdat, alloc_order, reclaim_order,
> > > classzone_idx);
> > >
> > > /* Read the new order and classzone_idx */
> > > alloc_order = reclaim_order = pgdat->kswapd_order;
> > > - classzone_idx = pgdat->kswapd_classzone_idx;
> > > + classzone_idx = kswapd_classzone_idx(pgdat, 0);
> > > pgdat->kswapd_order = 0;
> > > - pgdat->kswapd_classzone_idx = 0;
> > > + pgdat->kswapd_classzone_idx = MAX_NR_ZONES;
> > >
> > > ret = try_to_freeze();
> > > if (kthread_should_stop())
> > > @@ -3486,9 +3508,6 @@ static int kswapd(void *p)
> > > reclaim_order = balance_pgdat(pgdat, alloc_order, classzone_idx);
> > > if (reclaim_order < alloc_order)
> > > goto kswapd_try_sleep;
> >
> > If we fail order-5 request, can we then give up order-5, and
> > try order-3 if requested, after napping?
> >
>
> That has no bearing upon this patch. At this point, kswapd has stopped
> reclaiming at the requested order and is preparing to sleep. If there is
> a parallel request for order-3 while it's sleeping, it'll wake and start
> reclaiming at order-3 as requested.
>
Right, but the order-3 request can also come up while kswapd is active and
gives up order-5.
thanks
Hillf
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
