The presense of free per-cpu pages appear to cause fragmentation because
contiguous free blocks do not merge with their buddies. This can skew the
results between runs a lot because how many HugeTLB pages there are available
depends on luck. This patch was applied to both stock and anti-frag kernels
to give more consistant results.
Signed-off-by: Mel Gorman <[email protected]>
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.16-rc1-mm3-902_highorderoom/mm/page_alloc.c linux-2.6.16-rc1-mm3-903_drainpercpu/mm/page_alloc.c
--- linux-2.6.16-rc1-mm3-902_highorderoom/mm/page_alloc.c 2006-01-26 18:15:07.000000000 +0000
+++ linux-2.6.16-rc1-mm3-903_drainpercpu/mm/page_alloc.c 2006-01-26 18:15:49.000000000 +0000
@@ -623,7 +623,8 @@ void drain_remote_pages(void)
}
#endif
-#if defined(CONFIG_PM) || defined(CONFIG_HOTPLUG_CPU)
+#if defined(CONFIG_PM) || \
+ defined(CONFIG_HOTPLUG_CPU)
static void __drain_pages(unsigned int cpu)
{
unsigned long flags;
@@ -685,6 +686,27 @@ void drain_local_pages(void)
__drain_pages(smp_processor_id());
local_irq_restore(flags);
}
+
+void smp_drain_local_pages(void *arg)
+{
+ drain_local_pages();
+}
+
+/*
+ * Spill all the per-cpu pages from all CPUs back into the buddy allocator
+ */
+void drain_all_local_pages(void)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ __drain_pages(smp_processor_id());
+ local_irq_restore(flags);
+
+ smp_call_function(smp_drain_local_pages, NULL, 0, 1);
+}
+#else
+void drain_all_local_pages(void) {}
#endif /* CONFIG_PM */
static void zone_statistics(struct zonelist *zonelist, struct zone *z, int cpu)
@@ -1073,6 +1095,9 @@ rebalance:
did_some_progress = try_to_free_pages(zonelist->zones, gfp_mask);
+ if (order > 3)
+ drain_all_local_pages();
+
p->reclaim_state = NULL;
p->flags &= ~PF_MEMALLOC;
-
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