Commit 590ccea8 authored by Mel Gorman's avatar Mel Gorman Committed by Andrew Morton
Browse files

mm: compaction: update pageblock skip when first migration candidate is not at the start 

isolate_migratepages_block should mark a pageblock as skip if scanning
started on an aligned pageblock boundary but it only updates the skip flag
if the first migration candidate is also aligned.  Tracing during a
compaction stress load (mmtests: workload-usemem-stress-numa-compact) that
many pageblocks are not marked skip causing excessive scanning of blocks
that had been recently checked.  Update pageblock skip based on
"valid_page" which is set if scanning started on a pageblock boundary.

[mgorman@techsingularity.net: fix handling of skip bit]
  Link: https://lkml.kernel.org/r/20230602111622.swtxhn6lu2qwgrwq@techsingularity.net
Link: https://lkml.kernel.org/r/20230515113344.6869-4-mgorman@techsingularity.net


Signed-off-by: default avatarMel Gorman <mgorman@techsingularity.net>
Tested-by: default avatarRaghavendra K T <raghavendra.kt@amd.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Chuyi Zhou <zhouchuyi@bytedance.com>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 9ecc5fc5

mm/compaction.c

+12 −11
Original line number Diff line number Diff line
@@ -392,18 +392,14 @@ void reset_isolation_suitable(pg_data_t *pgdat) 
 * Sets the pageblock skip bit if it was clear. Note that this is a hint as

 * locks are not required for read/writers. Returns true if it was already set.

 */

static bool test_and_set_skip(struct compact_control *cc, struct page *page,

							unsigned long pfn)

static bool test_and_set_skip(struct compact_control *cc, struct page *page)

{

	bool skip;



	/* Do no update if skip hint is being ignored */

	/* Do not update if skip hint is being ignored */

	if (cc->ignore_skip_hint)

		return false;



	if (!pageblock_aligned(pfn))

		return false;



	skip = get_pageblock_skip(page);

	if (!skip && !cc->no_set_skip_hint)

		set_pageblock_skip(page);
@@ -470,8 +466,7 @@ static void update_cached_migrate(struct compact_control *cc, unsigned long pfn) 
{

}



static bool test_and_set_skip(struct compact_control *cc, struct page *page,

							unsigned long pfn)

static bool test_and_set_skip(struct compact_control *cc, struct page *page)

{

	return false;

}
@@ -1074,12 +1069,18 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, 


			lruvec_memcg_debug(lruvec, page_folio(page));



			/* Try get exclusive access under lock */

			if (!skip_updated) {

			/*

			 * Try get exclusive access under lock. If marked for

			 * skip, the scan is aborted unless the current context

			 * is a rescan to reach the end of the pageblock.

			 */

			if (!skip_updated && valid_page) {

				skip_updated = true;

				if (test_and_set_skip(cc, page, low_pfn))

				if (test_and_set_skip(cc, valid_page) &&

				    !cc->finish_pageblock) {

					goto isolate_abort;

				}

			}



			/*

			 * Page become compound since the non-locked check,