The patch titled
Subject: mm, thp: tweak reclaim/compaction effort of local-only and all-node allocations
has been added to the -mm tree. Its filename is
mm-thp-tweak-reclaim-compaction-effort-of-local-only-and-all-node-allocations.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-tweak-reclaim-compaction-effort-of-local-only-and-all-node-allocations.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-tweak-reclaim-compaction-effort-of-local-only-and-all-node-allocations.patch
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------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm, thp: tweak reclaim/compaction effort of local-only and all-node allocations
THP page faults now attempt a __GFP_THISNODE allocation first, which
should only compact existing free memory, followed by another attempt that
can allocate from any node using reclaim/compaction effort specified by
global defrag setting and madvise.
This patch makes the following changes to the scheme:
- before the patch, the first allocation relies on a check for pageblock
order and __GFP_IO to prevent excessive reclaim. This however affects
also the second attempt, which is not limited to single node. Instead
of that, reuse the existing check for costly order __GFP_NORETRY
allocations, and make sure the first THP attempt uses __GFP_NORETRY. As
a side-effect, all costly order __GFP_NORETRY allocations will bail out
if compaction needs reclaim, while previously they only bailed out when
compaction was deferred due to previous failures. This should be still
acceptable within the __GFP_NORETRY semantics.
- before the patch, the second allocation attempt (on all nodes) was
passing __GFP_NORETRY. This is redundant as the check for pageblock
order (discussed above) was stronger. It's also contrary to
madvise(MADV_HUGEPAGE) which means some effort to allocate THP is
requested. After this patch, the second attempt doesn't pass
__GFP_THISNODE nor __GFP_NORETRY.
To sum up, THP page faults now try the following attempts:
1. local node only THP allocation with no reclaim, just compaction.
2. for madvised VMA's or when synchronous compaction is enabled always - THP
allocation from any node with effort determined by global defrag setting
and VMA madvise
3. fallback to base pages on any node
Link: http://lkml.kernel.org/r/08a3f4dd-c3ce-0009-86c5-9ee51aba8557@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mempolicy.c | 10 +++++++---
mm/page_alloc.c | 24 +++++-------------------
2 files changed, 12 insertions(+), 22 deletions(-)
--- a/mm/mempolicy.c~mm-thp-tweak-reclaim-compaction-effort-of-local-only-and-all-node-allocations
+++ a/mm/mempolicy.c
@@ -2129,18 +2129,22 @@ alloc_pages_vma(gfp_t gfp, int order, st
nmask = policy_nodemask(gfp, pol);
if (!nmask || node_isset(hpage_node, *nmask)) {
mpol_cond_put(pol);
+ /*
+ * First, try to allocate THP only on local node, but
+ * don't reclaim unnecessarily, just compact.
+ */
page = __alloc_pages_node(hpage_node,
- gfp | __GFP_THISNODE, order);
+ gfp | __GFP_THISNODE | __GFP_NORETRY, order);
/*
* If hugepage allocations are configured to always
* synchronous compact or the vma has been madvised
* to prefer hugepage backing, retry allowing remote
- * memory as well.
+ * memory with both reclaim and compact as well.
*/
if (!page && (gfp & __GFP_DIRECT_RECLAIM))
page = __alloc_pages_node(hpage_node,
- gfp | __GFP_NORETRY, order);
+ gfp, order);
goto out;
}
--- a/mm/page_alloc.c~mm-thp-tweak-reclaim-compaction-effort-of-local-only-and-all-node-allocations
+++ a/mm/page_alloc.c
@@ -4481,8 +4481,11 @@ retry_cpuset:
if (page)
goto got_pg;
- if (order >= pageblock_order && (gfp_mask & __GFP_IO) &&
- !(gfp_mask & __GFP_RETRY_MAYFAIL)) {
+ /*
+ * Checks for costly allocations with __GFP_NORETRY, which
+ * includes some THP page fault allocations
+ */
+ if (costly_order && (gfp_mask & __GFP_NORETRY)) {
/*
* If allocating entire pageblock(s) and compaction
* failed because all zones are below low watermarks
@@ -4503,23 +4506,6 @@ retry_cpuset:
if (compact_result == COMPACT_SKIPPED ||
compact_result == COMPACT_DEFERRED)
goto nopage;
- }
-
- /*
- * Checks for costly allocations with __GFP_NORETRY, which
- * includes THP page fault allocations
- */
- if (costly_order && (gfp_mask & __GFP_NORETRY)) {
- /*
- * If compaction is deferred for high-order allocations,
- * it is because sync compaction recently failed. If
- * this is the case and the caller requested a THP
- * allocation, we do not want to heavily disrupt the
- * system, so we fail the allocation instead of entering
- * direct reclaim.
- */
- if (compact_result == COMPACT_DEFERRED)
- goto nopage;
/*
* Looks like reclaim/compaction is worth trying, but
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
mm-thp-tweak-reclaim-compaction-effort-of-local-only-and-all-node-allocations.patch
