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mm/migrate: demote pages during reclaim

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This is mostly derived from a patch from Yang Shi:

	https://lore.kernel.org/linux-mm/1560468577-101178-10-git-send-email-yang.shi@linux.alibaba.com/

Add code to the reclaim path (shrink_page_list()) to "demote" data to
another NUMA node instead of discarding the data.  This always avoids the
cost of I/O needed to read the page back in and sometimes avoids the
writeout cost when the page is dirty.

A second pass through shrink_page_list() will be made if any demotions
fail.  This essentially falls back to normal reclaim behavior in the case
that demotions fail.  Previous versions of this patch may have simply
failed to reclaim pages which were eligible for demotion but were unable
to be demoted in practice.

For some cases, for example, MADV_PAGEOUT, the pages are always discarded
instead of demoted to follow the kernel API definition.  Because
MADV_PAGEOUT is defined as freeing specified pages regardless in which
tier they are.

Note: This just adds the start of infrastructure for migration.  It is
actually disabled next to the FIXME in migrate_demote_page_ok().

[dave.hansen@linux.intel.com: v11]
  Link: https://lkml.kernel.org/r/20210715055145.195411-5-ying.huang@intel.com
  Link: https://lkml.kernel.org/r/20210721063926.3024591-4-ying.huang@intel.com

Link: https://lkml.kernel.org/r/20210715055145.195411-5-ying.huang@intel.com
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Wei Xu <weixugc@google.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dave Hansen
2021-09-02 14:59:16 -07:00
committed by Linus Torvalds
parent 5ac95884a7
commit 26aa2d199d
3 changed files with 96 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/migrate.h
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@@ -28,6 +28,7 @@ enum migrate_reason {
MR_NUMA_MISPLACED,
MR_CONTIG_RANGE,
MR_LONGTERM_PIN,
MR_DEMOTION,
MR_TYPES
};
@@ -167,6 +168,14 @@ struct migrate_vma {
int migrate_vma_setup(struct migrate_vma *args);
void migrate_vma_pages(struct migrate_vma *migrate);
void migrate_vma_finalize(struct migrate_vma *migrate);
int next_demotion_node(int node);
#else /* CONFIG_MIGRATION disabled: */
static inline int next_demotion_node(int node)
{
return NUMA_NO_NODE;
}
#endif /* CONFIG_MIGRATION */