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,david@redhat.com
Subject: [RFC][PATCH 1/9] mm/numa: node demotion data structure and lookup
Date: Wed, 07 Oct 2020 09:17:38 -0700 [thread overview]
Message-ID: <20201007161738.403BFCD7@viggo.jf.intel.com> (raw)
In-Reply-To: <20201007161736.ACC6E387@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>
Cc: David Hildenbrand <david@redhat.com>
--
changes in July 2020:
- Remove loop from next_demotion_node() and get_online_mems().
This means that the node returned by next_demotion_node()
might now be offline, but the worst case is that the
allocation fails. That's fine since it is transient.
---
b/mm/migrate.c | 16 ++++++++++++++++
1 file changed, 16 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 2020-10-07 09:15:25.978642454 -0700
+++ b/mm/migrate.c 2020-10-07 09:15:25.989642454 -0700
@@ -1161,6 +1161,22 @@ 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; NUMA_NO_NODE if @node is terminal. This does not keep
+ * @node online or guarantee that it *continues* to be the next demotion
+ * target.
+ */
+int next_demotion_node(int node)
+{
+ return node_demotion[node];
+}
+
/*
* Obtain the lock on page, remove all ptes and migrate the page
* to the newly allocated page in newpage.
_
next prev parent reply other threads:[~2020-10-07 16:18 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-07 16:17 [RFC][PATCH 0/9] [v4][RESEND] Migrate Pages in lieu of discard Dave Hansen
2020-10-07 16:17 ` Dave Hansen [this message]
2020-10-07 16:17 ` [RFC][PATCH 2/9] mm/numa: automatically generate node migration order Dave Hansen
2020-10-07 16:17 ` [RFC][PATCH 3/9] mm/migrate: update migration order during on hotplug events Dave Hansen
2020-10-07 18:08 ` osalvador
2020-10-07 16:17 ` [RFC][PATCH 4/9] mm/migrate: make migrate_pages() return nr_succeeded Dave Hansen
2020-10-07 16:17 ` [RFC][PATCH 5/9] mm/migrate: demote pages during reclaim Dave Hansen
2020-10-27 15:29 ` Oscar Salvador
2020-10-27 16:53 ` Yang Shi
2020-10-07 16:17 ` [RFC][PATCH 6/9] mm/vmscan: add page demotion counter Dave Hansen
2020-10-19 7:37 ` Huang, Ying
2020-10-27 16:41 ` Yang Shi
2020-10-28 1:25 ` Huang, Ying
2020-10-07 16:17 ` [RFC][PATCH 7/9] mm/vmscan: Consider anonymous pages without swap Dave Hansen
2020-10-29 8:14 ` Oscar Salvador
2020-10-29 14:33 ` Dave Hansen
2020-10-29 15:57 ` Yang Shi
2020-10-29 19:08 ` osalvador
2020-10-29 19:30 ` Yang Shi
2020-10-07 16:17 ` [RFC][PATCH 8/9] mm/vmscan: never demote for memcg reclaim Dave Hansen
2020-10-07 16:17 ` [RFC][PATCH 9/9] mm/migrate: new zone_reclaim_mode to enable reclaim migration Dave Hansen
2020-10-12 21:30 ` [RFC][PATCH 0/9] [v4][RESEND] Migrate Pages in lieu of discard Yang Shi
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