mm: vmscan: move logic from balance_pgdat() to kswapd_shrink_zone() (7c954f6d) · Commits · 戴 / test

mm/vmscan.c

+54 −56

Original line number	Diff line number	Diff line
		@@ -2709,18 +2709,53 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
		* This is used to determine if the scanning priority needs to be raised.
		*/
		static bool kswapd_shrink_zone(struct zone *zone,
		int classzone_idx,
		struct scan_control *sc,
		unsigned long lru_pages,
		unsigned long *nr_attempted)
		{
		unsigned long nr_slab;
		int testorder = sc->order;
		unsigned long balance_gap;
		struct reclaim_state *reclaim_state = current->reclaim_state;
		struct shrink_control shrink = {
		.gfp_mask = sc->gfp_mask,
		};
		bool lowmem_pressure;

		/* Reclaim above the high watermark. */
		sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone));

		/*
		* Kswapd reclaims only single pages with compaction enabled. Trying
		* too hard to reclaim until contiguous free pages have become
		* available can hurt performance by evicting too much useful data
		* from memory. Do not reclaim more than needed for compaction.
		*/
		if (IS_ENABLED(CONFIG_COMPACTION) && sc->order &&
		compaction_suitable(zone, sc->order) !=
		COMPACT_SKIPPED)
		testorder = 0;

		/*
		* We put equal pressure on every zone, unless one zone has way too
		* many pages free already. The "too many pages" is defined as the
		* high wmark plus a "gap" where the gap is either the low
		* watermark or 1% of the zone, whichever is smaller.
		*/
		balance_gap = min(low_wmark_pages(zone),
		(zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
		KSWAPD_ZONE_BALANCE_GAP_RATIO);

		/*
		* If there is no low memory pressure or the zone is balanced then no
		* reclaim is necessary
		*/
		lowmem_pressure = (buffer_heads_over_limit && is_highmem(zone));
		if (!lowmem_pressure && zone_balanced(zone, testorder,
		balance_gap, classzone_idx))
		return true;

		shrink_zone(zone, sc);

		reclaim_state->reclaimed_slab = 0;
		@@ -2735,6 +2770,18 @@ static bool kswapd_shrink_zone(struct zone *zone,

		zone_clear_flag(zone, ZONE_WRITEBACK);

		/*
		* If a zone reaches its high watermark, consider it to be no longer
		* congested. It's possible there are dirty pages backed by congested
		* BDIs but as pressure is relieved, speculatively avoid congestion
		* waits.
		*/
		if (!zone->all_unreclaimable &&
		zone_balanced(zone, testorder, 0, classzone_idx)) {
		zone_clear_flag(zone, ZONE_CONGESTED);
		zone_clear_flag(zone, ZONE_TAIL_LRU_DIRTY);
		}

		return sc->nr_scanned >= sc->nr_to_reclaim;
		}

		@@ -2870,8 +2917,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
		*/
		for (i = 0; i <= end_zone; i++) {
		struct zone *zone = pgdat->node_zones + i;
		int testorder;
		unsigned long balance_gap;

		if (!populated_zone(zone))
		continue;
		@@ -2892,63 +2937,16 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
		sc.nr_reclaimed += nr_soft_reclaimed;

		/*
		* We put equal pressure on every zone, unless
		* one zone has way too many pages free
		* already. The "too many pages" is defined
		* as the high wmark plus a "gap" where the
		* gap is either the low watermark or 1%
		* of the zone, whichever is smaller.
		*/
		balance_gap = min(low_wmark_pages(zone),
		(zone->managed_pages +
		KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
		KSWAPD_ZONE_BALANCE_GAP_RATIO);
		/*
		* Kswapd reclaims only single pages with compaction
		* enabled. Trying too hard to reclaim until contiguous
		* free pages have become available can hurt performance
		* by evicting too much useful data from memory.
		* Do not reclaim more than needed for compaction.
		*/
		testorder = order;
		if (IS_ENABLED(CONFIG_COMPACTION) && order &&
		compaction_suitable(zone, order) !=
		COMPACT_SKIPPED)
		testorder = 0;

		if ((buffer_heads_over_limit && is_highmem_idx(i)) \|\|
		!zone_balanced(zone, testorder,
		balance_gap, end_zone)) {
		/*
		* There should be no need to raise the
		* scanning priority if enough pages are
		* already being scanned that high
		* watermark would be met at 100% efficiency.
		* There should be no need to raise the scanning
		* priority if enough pages are already being scanned
		* that that high watermark would be met at 100%
		* efficiency.
		*/
		if (kswapd_shrink_zone(zone, &sc, lru_pages,
		&nr_attempted))
		if (kswapd_shrink_zone(zone, end_zone, &sc,
		lru_pages, &nr_attempted))
		raise_priority = false;
		}

		if (zone->all_unreclaimable) {
		if (end_zone && end_zone == i)
		end_zone--;
		continue;
		}

		if (zone_balanced(zone, testorder, 0, end_zone))
		/*
		* If a zone reaches its high watermark,
		* consider it to be no longer congested. It's
		* possible there are dirty pages backed by
		* congested BDIs but as pressure is relieved,
		* speculatively avoid congestion waits
		* or writing pages from kswapd context.
		*/
		zone_clear_flag(zone, ZONE_CONGESTED);
		zone_clear_flag(zone, ZONE_TAIL_LRU_DIRTY);
		}

		/*
		* If the low watermark is met there is no need for processes
		* to be throttled on pfmemalloc_wait as they should not be

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