+ mm-page_alloc-track-range-of-active-pcp-lists-during-bulk-free.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/page_alloc: track range of active PCP lists during bulk free
has been added to the -mm tree.  Its filename is
     mm-page_alloc-track-range-of-active-pcp-lists-during-bulk-free.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-track-range-of-active-pcp-lists-during-bulk-free.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-track-range-of-active-pcp-lists-during-bulk-free.patch

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------------------------------------------------------
From: Mel Gorman <mgorman@techsingularity.net>
Subject: mm/page_alloc: track range of active PCP lists during bulk free

free_pcppages_bulk() frees pages in a round-robin fashion.  Originally,
this was dealing only with migratetypes but storing high-order pages means
that there can be many more empty lists that are uselessly checked.  Track
the minimum and maximum active pindex to reduce the search space.

Link: https://lkml.kernel.org/r/20220215145111.27082-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_alloc.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

--- a/mm/page_alloc.c~mm-page_alloc-track-range-of-active-pcp-lists-during-bulk-free
+++ a/mm/page_alloc.c
@@ -1450,6 +1450,8 @@ static void free_pcppages_bulk(struct zo
 					struct per_cpu_pages *pcp)
 {
 	int pindex = 0;
+	int min_pindex = 0;
+	int max_pindex = NR_PCP_LISTS - 1;
 	int batch_free = 0;
 	int nr_freed = 0;
 	unsigned int order;
@@ -1478,10 +1480,17 @@ static void free_pcppages_bulk(struct zo
 			if (++pindex == NR_PCP_LISTS)
 				pindex = 0;
 			list = &pcp->lists[pindex];
-		} while (list_empty(list));
+			if (!list_empty(list))
+				break;
+
+			if (pindex == max_pindex)
+				max_pindex--;
+			if (pindex == min_pindex)
+				min_pindex++;
+		} while (1);
 
 		/* This is the only non-empty list. Free them all. */
-		if (batch_free == NR_PCP_LISTS)
+		if (batch_free >= max_pindex - min_pindex)
 			batch_free = count;
 
 		order = pindex_to_order(pindex);
_

Patches currently in -mm which might be from mgorman@techsingularity.net are

mm-page_alloc-fetch-the-correct-pcp-buddy-during-bulk-free.patch
mm-page_alloc-track-range-of-active-pcp-lists-during-bulk-free.patch
mm-page_alloc-simplify-how-many-pages-are-selected-per-pcp-list-during-bulk-free.patch
mm-page_alloc-free-pages-in-a-single-pass-during-bulk-free.patch
mm-page_alloc-limit-number-of-high-order-pages-on-pcp-during-bulk-free.patch