From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
To: 'Mel Gorman' <mgorman@techsingularity.net>
Cc: 'Andrew Morton' <akpm@linux-foundation.org>,
'Shantanu Goel' <sgoel01@yahoo.com>, 'Chris Mason' <clm@fb.com>,
'Johannes Weiner' <hannes@cmpxchg.org>,
'Vlastimil Babka' <vbabka@suse.cz>,
'LKML' <linux-kernel@vger.kernel.org>,
'Linux-MM' <linux-mm@kvack.org>
Subject: Re: [PATCH 3/3] mm, vmscan: Prevent kswapd sleeping prematurely due to mismatched classzone_idx
Date: Thu, 16 Feb 2017 16:21:04 +0800 [thread overview]
Message-ID: <001f01d2882d$9dd14850$d973d8f0$@alibaba-inc.com> (raw)
In-Reply-To: <20170216081039.ukbxl2b4khnwwbic@techsingularity.net>
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
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next prev parent reply other threads:[~2017-02-16 8:21 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-15 9:22 [PATCH 0/3] Reduce amount of time kswapd sleeps prematurely Mel Gorman
2017-02-15 9:22 ` [PATCH 1/3] mm, vmscan: fix zone balance check in prepare_kswapd_sleep Mel Gorman
2017-02-16 2:50 ` Hillf Danton
2017-02-22 7:00 ` Minchan Kim
2017-02-23 15:05 ` Mel Gorman
2017-02-24 1:17 ` Minchan Kim
2017-02-24 9:11 ` Mel Gorman
2017-02-27 6:16 ` Minchan Kim
2017-02-15 9:22 ` [PATCH 2/3] mm, vmscan: Only clear pgdat congested/dirty/writeback state when balanced Mel Gorman
2017-02-15 9:22 ` [PATCH 3/3] mm, vmscan: Prevent kswapd sleeping prematurely due to mismatched classzone_idx Mel Gorman
2017-02-16 6:23 ` Hillf Danton
2017-02-16 8:10 ` Mel Gorman
2017-02-16 8:21 ` Hillf Danton [this message]
2017-02-16 9:32 ` Mel Gorman
2017-02-20 16:34 ` Vlastimil Babka
2017-02-21 4:10 ` Hillf Danton
2017-02-20 16:42 ` Vlastimil Babka
2017-02-23 15:01 ` Mel Gorman
2017-03-01 9:04 ` Vlastimil Babka
2017-02-15 20:30 ` [PATCH 0/3] Reduce amount of time kswapd sleeps prematurely Andrew Morton
2017-02-15 21:29 ` Mel Gorman
2017-02-15 21:56 ` Andrew Morton
2017-02-15 22:15 ` Mel Gorman
2017-02-15 22:00 ` Vlastimil Babka
2017-03-09 7:56 [PATCH 0/3] Reduce amount of time kswapd sleeps prematurely v2 Mel Gorman
2017-03-09 7:56 ` [PATCH 3/3] mm, vmscan: Prevent kswapd sleeping prematurely due to mismatched classzone_idx Mel Gorman
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