Messages in this thread Patch in this message | | | Subject | Re: [PATCH 04/27] mm, vmscan: Begin reclaiming pages on a per-node basis | From | Vlastimil Babka <> | Date | Wed, 22 Jun 2016 16:04:34 +0200 |
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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; > + } > > /* > * Take care memory controller reclaiming has small influence > @@ -2594,8 +2618,8 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) > */ > if (IS_ENABLED(CONFIG_COMPACTION) && > sc->order > PAGE_ALLOC_COSTLY_ORDER && > - zonelist_zone_idx(z) <= requested_highidx && > - compaction_ready(zone, sc->order, requested_highidx)) { > + zonelist_zone_idx(z) <= classzone_idx && > + compaction_ready(zone, sc->order, classzone_idx)) { > sc->compaction_ready = true; > continue; > } > @@ -2615,7 +2639,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) > /* need some check for avoid more shrink_zone() */ > } > > - shrink_zone(zone, sc, zone_idx(zone) == classzone_idx); > + shrink_node(zone->zone_pgdat, sc, classzone_idx); > } > > /* > @@ -2647,6 +2671,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, > int initial_priority = sc->priority; > unsigned long total_scanned = 0; > unsigned long writeback_threshold; > + enum zone_type classzone_idx = sc->reclaim_idx;
Hmm, try_to_free_mem_cgroup_pages() seems to call this with sc->reclaim_idx not explicitly inirialized (e.g. 0). And shrink_all_memory() as well. I probably didn't check them in v6 and pointed out only try_to_free_pages() (which is now OK), sorry.
> retry: > delayacct_freepages_start(); > > @@ -2657,7 +2682,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, > vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, > sc->priority); > sc->nr_scanned = 0; > - shrink_zones(zonelist, sc); > + shrink_zones(zonelist, sc, classzone_idx);
Looks like classzone_idx here is only used here to pass to shrink_zones() unchanged, which means it can just use it directly without a new param?
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