[PATCHv1 6/8] xen/balloon: only hotplug additional memory if required

[David Vrabel]

Now that we track the total number of pages (included hotplugged
regions), it is easy to determine if more memory needs to be
hotplugged.

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
 drivers/xen/balloon.c |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 960ac79..dd41da8 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -241,12 +241,22 @@ static void release_memory_resource(struct resource *resource)
  * bit set). Real size of added memory is established at page onlining stage.
  */
 
-static enum bp_state reserve_additional_memory(long credit)
+static enum bp_state reserve_additional_memory(void)
 {
+	long credit;
 	struct resource *resource;
 	int nid, rc;
 	unsigned long balloon_hotplug;
 
+	credit = balloon_stats.target_pages - balloon_stats.total_pages;
+
+	/*
+	 * Already hotplugged enough pages?  Wait for them to be
+	 * onlined.
+	 */
+	if (credit <= 0)
+		return BP_EAGAIN;
+
 	balloon_hotplug = round_up(credit, PAGES_PER_SECTION);
 
 	resource = additional_memory_resource(balloon_hotplug * PAGE_SIZE);
@@ -316,7 +326,7 @@ static struct notifier_block xen_memory_nb = {
 	.priority = 0
 };
 #else
-static enum bp_state reserve_additional_memory(long credit)
+static enum bp_state reserve_additional_memory(void)
 {
 	balloon_stats.target_pages = balloon_stats.current_pages;
 	return BP_DONE;
@@ -483,7 +493,7 @@ static void balloon_process(struct work_struct *work)
 			if (balloon_is_inflated())
 				state = increase_reservation(credit);
 			else
-				state = reserve_additional_memory(credit);
+				state = reserve_additional_memory();
 		}
 
 		if (credit < 0)
-- 
1.7.10.4

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