The patch titled
Subject: mm, compaction: skip pageblocks with reserved pages
has been added to the -mm tree. Its filename is
mm-compaction-skip-pageblocks-with-reserved-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-skip-pageblocks-with-reserved-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-skip-pageblocks-with-reserved-pages.patch
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------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm, compaction: skip pageblocks with reserved pages
Reserved pages are set at boot time, tend to be clustered and almost never
become unreserved. When isolating pages for either migration sources or
target, skip the entire pageblock is one PageReserved page is encountered
on the grounds that it is highly probable the entire pageblock is
reserved.
The performance impact is relative to the number of reserved pages in the
system and their location so it'll be variable but intuitively it should
make sense. If the memblock allocator was ever changed to spread reserved
pages throughout the address space then this patch would be impaired but
it would also be considered a bug given that such a change would ruin
fragmentation.
On both 1-socket and 2-socket machines, scan rates are reduced slightly on
workloads that intensively allocate THP while the system is fragmented.
Link: http://lkml.kernel.org/r/20190104125011.16071-7-mgorman@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/compaction.c~mm-compaction-skip-pageblocks-with-reserved-pages
+++ a/mm/compaction.c
@@ -484,6 +484,15 @@ static unsigned long isolate_freepages_b
goto isolate_fail;
}
+ /*
+ * A reserved page is never freed and tend to be clustered in
+ * the same pageblock. Skip the block.
+ */
+ if (PageReserved(page)) {
+ blockpfn = end_pfn;
+ break;
+ }
+
if (!PageBuddy(page))
goto isolate_fail;
@@ -827,6 +836,13 @@ isolate_migratepages_block(struct compac
goto isolate_success;
}
+ /*
+ * A reserved page is never freed and tend to be
+ * clustered in the same pageblocks. Skip the block.
+ */
+ if (PageReserved(page))
+ low_pfn = end_pfn;
+
goto isolate_fail;
}
_
Patches currently in -mm which might be from mgorman@xxxxxxxxxxxxxxxxxxx are
mm-page_alloc-do-not-wake-kswapd-with-zone-lock-held.patch
mm-compaction-shrink-compact_control.patch
mm-compaction-rearrange-compact_control.patch
mm-compaction-remove-last_migrated_pfn-from-compact_control.patch
mm-compaction-remove-unnecessary-zone-parameter-in-some-instances.patch
mm-compaction-rename-map_pages-to-split_map_pages.patch
mm-compaction-skip-pageblocks-with-reserved-pages.patch
mm-migrate-immediately-fail-migration-of-a-page-with-no-migration-handler.patch
mm-compaction-always-finish-scanning-of-a-full-pageblock.patch
mm-compaction-use-the-page-allocator-bulk-free-helper-for-lists-of-pages.patch
mm-compaction-ignore-the-fragmentation-avoidance-boost-for-isolation-and-compaction.patch
mm-compaction-use-free-lists-to-quickly-locate-a-migration-source.patch
mm-compaction-keep-migration-source-private-to-a-single-compaction-instance.patch
mm-compaction-use-free-lists-to-quickly-locate-a-migration-target.patch
mm-compaction-avoid-rescanning-the-same-pageblock-multiple-times.patch
mm-compaction-finish-pageblock-scanning-on-contention.patch
mm-compaction-check-early-for-huge-pages-encountered-by-the-migration-scanner.patch
mm-compaction-keep-cached-migration-pfns-synced-for-unusable-pageblocks.patch
mm-compaction-rework-compact_should_abort-as-compact_check_resched.patch
mm-compaction-do-not-consider-a-need-to-reschedule-as-contention.patch
mm-compaction-reduce-unnecessary-skipping-of-migration-target-scanner.patch
mm-compaction-round-robin-the-order-while-searching-the-free-lists-for-a-target.patch
mm-compaction-sample-pageblocks-for-free-pages.patch
mm-compaction-be-selective-about-what-pageblocks-to-clear-skip-hints.patch
mm-compaction-capture-a-page-under-direct-compaction.patch
mm-compaction-do-not-direct-compact-remote-memory.patch
