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authorVlastimil Babka <vbabka@suse.cz>2020-01-14 03:29:04 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-14 05:19:01 +0300
commitcc638f329ef605f5c2a57b87dd8e584e9d5f4c2f (patch)
tree0774ca988de319a2a4ccfa61888abc3af1cfcf2d /mm
parentb3a987b0264d3ddbb24293ebff10eddfc472f653 (diff)
downloadlinux-cc638f329ef605f5c2a57b87dd8e584e9d5f4c2f.tar.xz
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@suse.cz Fixes: b39d0ee2632d ("mm, page_alloc: avoid expensive reclaim when compaction may not succeed") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/mempolicy.c10
-rw-r--r--mm/page_alloc.c24
2 files changed, 12 insertions, 22 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 067cf7d3daf5..b2920ae87a61 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2148,18 +2148,22 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
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;
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4785a8a2040e..409be5ec7e2c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4476,8 +4476,11 @@ 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
@@ -4498,23 +4501,6 @@ 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