Commit b2ac6aa8 authored by David Vrabel's avatar David Vrabel
Browse files

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: default avatarDavid Vrabel <david.vrabel@citrix.com>
Reviewed-by: default avatarDaniel 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.
parent de5a77d8

drivers/xen/balloon.c

+19 −4
Original line number Diff line number Diff line
@@ -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 struct page *balloon_next_page(struct page *page) 


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 @@ static void release_memory_resource(struct resource *resource) 
	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 @@ static enum bp_state reserve_additional_memory(long credit) 


	balloon_stats.total_pages += balloon_hotplug;



	return BP_DONE;

	return BP_WAIT;

  err:

	release_memory_resource(resource);

	return BP_ECANCELED;
@@ -306,7 +321,7 @@ 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;
@@ -474,7 +489,7 @@ 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)

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