Re: [PATCH 14/40] autonuma: add page structure fields
From: Rik van Riel
Date: Fri Jun 29 2012 - 14:09:02 EST
On 06/28/2012 08:55 AM, Andrea Arcangeli wrote:
On 64bit archs, 20 bytes are used for async memory migration (specific
to the knuma_migrated per-node threads), and 4 bytes are used for the
thread NUMA false sharing detection logic.
This is a bad implementation due lack of time to do a proper one.
It is not ideal, no.
If you document what everything does, maybe somebody else
will understand the code well enough to help fix it.
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -136,6 +136,32 @@ struct page {
struct page *first_page; /* Compound tail pages */
};
+#ifdef CONFIG_AUTONUMA
+ /*
+ * FIXME: move to pgdat section along with the memcg and allocate
+ * at runtime only in presence of a numa system.
+ */
Once you fix it, could you fold the fix into this patch?
+ /*
+ * To modify autonuma_last_nid lockless the architecture,
+ * needs SMP atomic granularity< sizeof(long), not all archs
+ * have that, notably some ancient alpha (but none of those
+ * should run in NUMA systems). Archs without that requires
+ * autonuma_last_nid to be a long.
+ */
+#if BITS_PER_LONG> 32
+ int autonuma_migrate_nid;
+ int autonuma_last_nid;
+#else
+#if MAX_NUMNODES>= 32768
+#error "too many nodes"
+#endif
+ /* FIXME: remember to check the updates are atomic */
+ short autonuma_migrate_nid;
+ short autonuma_last_nid;
+#endif
+ struct list_head autonuma_migrate_node;
+#endif
Please document what these fields mean.
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