xen/balloon: only hotplug additional memory if required
Now that we track the total number of pages (included hotplugged
regions), it is easy to determine if more memory needs to be
hotplugged.
Add a new BP_WAIT state to signal that the balloon process needs to
wait until kicked by the memory add notifier (when the new section is
onlined by userspace).
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
v3:
- Return BP_WAIT if enough sections are already hotplugged.
v2:
- New BP_WAIT status after adding new memory sections.
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index ac80547..ac6391bd 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -75,12 +75,14 @@
* balloon_process() state:
*
* BP_DONE: done or nothing to do,
+ * BP_WAIT: wait to be rescheduled,
* BP_EAGAIN: error, go to sleep,
* BP_ECANCELED: error, balloon operation canceled.
*/
enum bp_state {
BP_DONE,
+ BP_WAIT,
BP_EAGAIN,
BP_ECANCELED
};
@@ -167,6 +169,9 @@
static enum bp_state update_schedule(enum bp_state state)
{
+ if (state == BP_WAIT)
+ return BP_WAIT;
+
if (state == BP_ECANCELED)
return BP_ECANCELED;
@@ -231,12 +236,22 @@
kfree(resource);
}
-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_WAIT;
+
balloon_hotplug = round_up(credit, PAGES_PER_SECTION);
resource = additional_memory_resource(balloon_hotplug * PAGE_SIZE);
@@ -276,7 +291,7 @@
balloon_stats.total_pages += balloon_hotplug;
- return BP_DONE;
+ return BP_WAIT;
err:
release_memory_resource(resource);
return BP_ECANCELED;
@@ -306,7 +321,7 @@
.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;
@@ -474,7 +489,7 @@
if (balloon_is_inflated())
state = increase_reservation(credit);
else
- state = reserve_additional_memory(credit);
+ state = reserve_additional_memory();
}
if (credit < 0)