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From: Dave Hansen <dave.hansen@linux.intel.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org,Dave Hansen
	<dave.hansen@linux.intel.com>,yang.shi@linux.alibaba.com,rientjes@google.com,ying.huang@intel.com,dan.j.williams@intel.com
Subject: [RFC][PATCH 1/8] mm/numa: node demotion data structure and lookup
Date: Mon, 29 Jun 2020 16:45:05 -0700
Message-ID: <20200629234505.6ABCBDF4@viggo.jf.intel.com> (raw)
In-Reply-To: <20200629234503.749E5340@viggo.jf.intel.com>


From: Dave Hansen <dave.hansen@linux.intel.com>

Prepare for the kernel to auto-migrate pages to other memory nodes
with a user defined node migration table. This allows creating single
migration target for each NUMA node to enable the kernel to do NUMA
page migrations instead of simply reclaiming colder pages. A node
with no target is a "terminal node", so reclaim acts normally there.
The migration target does not fundamentally _need_ to be a single node,
but this implementation starts there to limit complexity.

If you consider the migration path as a graph, cycles (loops) in the
graph are disallowed.  This avoids wasting resources by constantly
migrating (A->B, B->A, A->B ...).  The expectation is that cycles will
never be allowed.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
---

 b/mm/migrate.c |   23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff -puN mm/migrate.c~0006-node-Define-and-export-memory-migration-path mm/migrate.c
--- a/mm/migrate.c~0006-node-Define-and-export-memory-migration-path	2020-06-29 16:34:36.849312609 -0700
+++ b/mm/migrate.c	2020-06-29 16:34:36.853312609 -0700
@@ -1159,6 +1159,29 @@ out:
 	return rc;
 }
 
+static int node_demotion[MAX_NUMNODES] = {[0 ...  MAX_NUMNODES - 1] = NUMA_NO_NODE};
+
+/**
+ * next_demotion_node() - Get the next node in the demotion path
+ * @node: The starting node to lookup the next node
+ *
+ * @returns: node id for next memory node in the demotion path hierarchy
+ * from @node; -1 if @node is terminal
+ */
+int next_demotion_node(int node)
+{
+	get_online_mems();
+	while (true) {
+		node = node_demotion[node];
+		if (node == NUMA_NO_NODE)
+			break;
+		if (node_online(node))
+			break;
+	}
+	put_online_mems();
+	return node;
+}
+
 /*
  * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move().  Work
  * around it.
_


  reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-29 23:45 [RFC][PATCH 0/8] Migrate Pages in lieu of discard Dave Hansen
2020-06-29 23:45 ` Dave Hansen [this message]
2020-06-29 23:45 ` [RFC][PATCH 2/8] mm/migrate: Defer allocating new page until needed Dave Hansen
2020-07-01  8:47   ` Greg Thelen
2020-07-01 14:46     ` Dave Hansen
2020-07-01 18:32       ` Yang Shi
2020-06-29 23:45 ` [RFC][PATCH 3/8] mm/vmscan: Attempt to migrate page in lieu of discard Dave Hansen
2020-07-01  0:47   ` David Rientjes
2020-07-01  1:29     ` Yang Shi
2020-07-01  5:41       ` David Rientjes
2020-07-01  8:54         ` Huang, Ying
2020-07-01 18:20           ` Dave Hansen
2020-07-01 19:50             ` David Rientjes
2020-07-02  1:50               ` Huang, Ying
2020-07-01 15:15         ` Dave Hansen
2020-07-01 17:21         ` Yang Shi
2020-07-01 19:45           ` David Rientjes
2020-07-02 10:02             ` Jonathan Cameron
2020-07-01  1:40     ` Huang, Ying
2020-07-01 16:48     ` Dave Hansen
2020-07-01 19:25       ` David Rientjes
2020-07-02  5:02         ` Huang, Ying
2020-06-29 23:45 ` [RFC][PATCH 4/8] mm/vmscan: add page demotion counter Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 5/8] mm/numa: automatically generate node migration order Dave Hansen
2020-06-30  8:22   ` Huang, Ying
2020-07-01 18:23     ` Dave Hansen
2020-07-02  1:20       ` Huang, Ying
2020-06-29 23:45 ` [RFC][PATCH 6/8] mm/vmscan: Consider anonymous pages without swap Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 7/8] mm/vmscan: never demote for memcg reclaim Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 8/8] mm/numa: new reclaim mode to enable reclaim-based migration Dave Hansen
2020-06-30  7:23   ` Huang, Ying
2020-06-30 17:50     ` Yang Shi
2020-07-01  0:48       ` Huang, Ying
2020-07-01  1:12         ` Yang Shi
2020-07-01  1:28           ` Huang, Ying
2020-07-01 16:02       ` Dave Hansen
2020-07-03  9:30   ` Huang, Ying
2020-06-30 18:36 ` [RFC][PATCH 0/8] Migrate Pages in lieu of discard Shakeel Butt
2020-06-30 18:51   ` Dave Hansen
2020-06-30 19:25     ` Shakeel Butt
2020-06-30 19:31       ` Dave Hansen
2020-07-01 14:24         ` [RFC] [PATCH " Zi Yan
2020-07-01 14:32           ` Dave Hansen

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