From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>
Cc: Rik van Riel <riel@surriel.com>,
Johannes Weiner <hannes@cmpxchg.org>,
LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH 04/27] mm, vmscan: Begin reclaiming pages on a per-node basis
Date: Wed, 22 Jun 2016 18:00:12 +0200 [thread overview]
Message-ID: <efa724ae-63fb-c09f-13a3-ca9a09849ae2@suse.cz> (raw)
In-Reply-To: <6eecdf50-7880-2bfe-5519-004a4beeece6@suse.cz>
On 06/22/2016 04:04 PM, Vlastimil Babka wrote:
> On 06/21/2016 04:15 PM, Mel Gorman wrote:
>> This patch makes reclaim decisions on a per-node basis. A reclaimer knows
>> what zone is required by the allocation request and skips pages from
>> higher zones. In many cases this will be ok because it's a GFP_HIGHMEM
>> request of some description. On 64-bit, ZONE_DMA32 requests will cause
>> some problems but 32-bit devices on 64-bit platforms are increasingly
>> rare. Historically it would have been a major problem on 32-bit with big
>> Highmem:Lowmem ratios but such configurations are also now rare and even
>> where they exist, they are not encouraged. If it really becomes a problem,
>> it'll manifest as very low reclaim efficiencies.
>>
>> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
>
> [...]
>
>> @@ -2540,14 +2559,14 @@ static inline bool compaction_ready(struct zone *zone, int order, int classzone_
>> * If a zone is deemed to be full of pinned pages then just give it a light
>> * scan then give up on it.
>> */
>> -static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
>> +static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc,
>> + enum zone_type classzone_idx)
>> {
>> struct zoneref *z;
>> struct zone *zone;
>> unsigned long nr_soft_reclaimed;
>> unsigned long nr_soft_scanned;
>> gfp_t orig_mask;
>> - enum zone_type requested_highidx = gfp_zone(sc->gfp_mask);
>>
>> /*
>> * If the number of buffer_heads in the machine exceeds the maximum
>> @@ -2560,15 +2579,20 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
>>
>> for_each_zone_zonelist_nodemask(zone, z, zonelist,
>> gfp_zone(sc->gfp_mask), sc->nodemask) {
>
> Using sc->reclaim_idx could be faster/nicer here than gfp_zone()?
> Although after "mm, vmscan: Update classzone_idx if buffer_heads_over_limit"
> there would need to be a variable for the highmem adjusted value - maybe reuse
> "requested_highidx"? Not important though.
>
>> - enum zone_type classzone_idx;
>> -
>> if (!populated_zone(zone))
>> continue;
>>
>> - classzone_idx = requested_highidx;
>> + /*
>> + * Note that reclaim_idx does not change as it is the highest
>> + * zone reclaimed from which for empty zones is a no-op but
>> + * classzone_idx is used by shrink_node to test if the slabs
>> + * should be shrunk on a given node.
>> + */
>> while (!populated_zone(zone->zone_pgdat->node_zones +
>> - classzone_idx))
>> + classzone_idx)) {
>> classzone_idx--;
>> + continue;
Oh and Michal's comment on Patch 20 made me realize that my objection to v6
about possible underflow of sc->reclaim_idx and classzone_idx seems to still
apply here for classzone_idx? Updated example: Normal zone allocation. A small
node 0 without Normal zone will get us classzone_idx == dma32. Node 1 next in
zonelist won't have dma/dma32 zones so we won't see node_zones + classzone_idx
populated, and the while loop will lead to underflow of classzone_idx.
I may be missing something, but I don't really see another way around it than
resetting classzone_idx to sc->reclaim_idx before the while loop.
next prev parent reply other threads:[~2016-06-22 16:00 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-21 14:15 [PATCH 00/27] Move LRU page reclaim from zones to nodes v7 Mel Gorman
2016-06-21 14:15 ` [PATCH 01/27] mm, vmstat: Add infrastructure for per-node vmstats Mel Gorman
2016-06-21 14:15 ` [PATCH 02/27] mm, vmscan: Move lru_lock to the node Mel Gorman
2016-06-21 14:15 ` [PATCH 03/27] mm, vmscan: Move LRU lists to node Mel Gorman
2016-06-22 12:50 ` Vlastimil Babka
2016-06-21 14:15 ` [PATCH 04/27] mm, vmscan: Begin reclaiming pages on a per-node basis Mel Gorman
2016-06-22 14:04 ` Vlastimil Babka
2016-06-22 16:00 ` Vlastimil Babka [this message]
2016-06-23 11:07 ` Mel Gorman
2016-06-23 11:13 ` Michal Hocko
2016-06-23 10:58 ` Mel Gorman
2016-06-21 14:15 ` [PATCH 05/27] mm, vmscan: Have kswapd only scan based on the highest requested zone Mel Gorman
2016-06-21 14:15 ` [PATCH 06/27] mm, vmscan: Make kswapd reclaim in terms of nodes Mel Gorman
2016-06-21 14:15 ` [PATCH 07/27] mm, vmscan: Remove balance gap Mel Gorman
2016-06-21 14:15 ` [PATCH 08/27] mm, vmscan: Simplify the logic deciding whether kswapd sleeps Mel Gorman
2016-06-22 15:30 ` Vlastimil Babka
2016-06-21 14:15 ` [PATCH 09/27] mm, vmscan: By default have direct reclaim only shrink once per node Mel Gorman
2016-06-21 14:15 ` [PATCH 10/27] mm, vmscan: Remove duplicate logic clearing node congestion and dirty state Mel Gorman
2016-06-21 14:15 ` [PATCH 11/27] mm: vmscan: Do not reclaim from kswapd if there is any eligible zone Mel Gorman
2016-06-21 14:15 ` [PATCH 12/27] mm, vmscan: Make shrink_node decisions more node-centric Mel Gorman
2016-06-22 13:20 ` Michal Hocko
2016-06-22 15:42 ` Vlastimil Babka
2016-06-21 14:15 ` [PATCH 13/27] mm, memcg: Move memcg limit enforcement from zones to nodes Mel Gorman
2016-06-22 13:15 ` Michal Hocko
2016-06-21 14:15 ` [PATCH 14/27] mm, workingset: Make working set detection node-aware Mel Gorman
2016-06-21 14:15 ` [PATCH 15/27] mm, page_alloc: Consider dirtyable memory in terms of nodes Mel Gorman
2016-06-22 14:15 ` Michal Hocko
2016-06-22 14:27 ` Michal Hocko
2016-06-23 12:53 ` Mel Gorman
2016-06-23 13:13 ` Michal Hocko
2016-06-21 14:15 ` [PATCH 16/27] mm: Move page mapped accounting to the node Mel Gorman
2016-06-21 22:32 ` Andrew Morton
2016-06-23 8:35 ` Mel Gorman
2016-06-22 14:35 ` Michal Hocko
2016-06-21 14:15 ` [PATCH 17/27] mm: Rename NR_ANON_PAGES to NR_ANON_MAPPED Mel Gorman
2016-06-22 14:28 ` Michal Hocko
2016-06-21 14:15 ` [PATCH 18/27] mm: Move most file-based accounting to the node Mel Gorman
2016-06-22 14:38 ` Michal Hocko
2016-06-21 14:15 ` [PATCH 19/27] mm: Move vmscan writes and file write " Mel Gorman
2016-06-22 14:40 ` Michal Hocko
2016-06-23 13:57 ` Mel Gorman
2016-06-23 14:06 ` Vlastimil Babka
2016-06-23 16:03 ` Mel Gorman
2016-06-21 14:15 ` [PATCH 20/27] mm, vmscan: Update classzone_idx if buffer_heads_over_limit Mel Gorman
2016-06-22 14:49 ` Michal Hocko
2016-06-21 14:16 ` [PATCH 21/27] mm, vmscan: Only wakeup kswapd once per node for the requested classzone Mel Gorman
2016-06-22 16:08 ` Vlastimil Babka
2016-06-21 14:16 ` [PATCH 22/27] mm: Convert zone_reclaim to node_reclaim Mel Gorman
2016-06-21 14:16 ` [PATCH 23/27] mm, vmscan: Add classzone information to tracepoints Mel Gorman
2016-06-21 14:16 ` [PATCH 24/27] mm, page_alloc: Remove fair zone allocation policy Mel Gorman
2016-06-21 14:16 ` [PATCH 25/27] mm: page_alloc: Cache the last node whose dirty limit is reached Mel Gorman
2016-06-21 14:16 ` [PATCH 26/27] mm: vmstat: Replace __count_zone_vm_events with a zone id equivalent Mel Gorman
2016-06-21 14:16 ` [PATCH 27/27] mm: vmstat: Account per-zone stalls and pages skipped during reclaim Mel Gorman
2016-06-23 10:26 ` [PATCH 00/27] Move LRU page reclaim from zones to nodes v7 Mel Gorman
2016-06-23 11:27 ` Michal Hocko
2016-06-23 12:33 ` Mel Gorman
2016-06-23 12:44 ` Michal Hocko
2016-06-23 21:45 ` Andrew Morton
2016-06-24 6:35 ` Balbir Singh
2016-06-24 7:50 ` Mel Gorman
2016-06-27 12:48 ` Balbir Singh
[not found] <02ed01d1c47a$49fbfbc0$ddf3f340$@alibaba-inc.com>
2016-06-12 7:33 ` [PATCH 04/27] mm, vmscan: Begin reclaiming pages on a per-node basis Hillf Danton
2016-06-14 14:47 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2016-06-09 18:04 [PATCH 00/27] Move LRU page reclaim from zones to nodes v6 Mel Gorman
2016-06-09 18:04 ` [PATCH 04/27] mm, vmscan: Begin reclaiming pages on a per-node basis Mel Gorman
2016-06-15 12:52 ` Vlastimil Babka
2016-04-15 9:13 [PATCH 00/27] Move LRU page reclaim from zones to nodes v5 Mel Gorman
2016-04-15 9:13 ` [PATCH 04/27] mm, vmscan: Begin reclaiming pages on a per-node basis Mel Gorman
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