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Subject[PATCHv3 05/10] xen/balloon: rationalize memory hotplug stats
Date
The stats used for memory hotplug make no sense and are fiddled with
in odd ways. Remove them and introduce total_pages to track the total
number of pages (both populated and unpopulated) including those within
hotplugged regions (note that this includes not yet onlined pages).

This will be used in a subsequent commit (xen/balloon: only hotplug
additional memory if required) when deciding whether additional memory
needs to be hotplugged.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
drivers/xen/balloon.c | 75 +++++++++------------------------------------------
include/xen/balloon.h | 5 +---
2 files changed, 13 insertions(+), 67 deletions(-)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 7ecbbc5..932d232 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -194,21 +194,6 @@ static enum bp_state update_schedule(enum bp_state state)
}

#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
-static long current_credit(void)
-{
- return balloon_stats.target_pages - balloon_stats.current_pages -
- balloon_stats.hotplug_pages;
-}
-
-static bool balloon_is_inflated(void)
-{
- if (balloon_stats.balloon_low || balloon_stats.balloon_high ||
- balloon_stats.balloon_hotplug)
- return true;
- else
- return false;
-}
-
static struct resource *additional_memory_resource(phys_addr_t size)
{
struct resource *res;
@@ -289,10 +274,7 @@ static enum bp_state reserve_additional_memory(long credit)
goto err;
}

- balloon_hotplug -= credit;
-
- balloon_stats.hotplug_pages += credit;
- balloon_stats.balloon_hotplug = balloon_hotplug;
+ balloon_stats.total_pages += balloon_hotplug;

return BP_DONE;
err:
@@ -308,11 +290,6 @@ static void xen_online_page(struct page *page)

__balloon_append(page);

- if (balloon_stats.hotplug_pages)
- --balloon_stats.hotplug_pages;
- else
- --balloon_stats.balloon_hotplug;
-
mutex_unlock(&balloon_mutex);
}

@@ -329,32 +306,22 @@ static struct notifier_block xen_memory_nb = {
.priority = 0
};
#else
-static long current_credit(void)
+static enum bp_state reserve_additional_memory(long credit)
{
- unsigned long target = balloon_stats.target_pages;
-
- target = min(target,
- balloon_stats.current_pages +
- balloon_stats.balloon_low +
- balloon_stats.balloon_high);
-
- return target - balloon_stats.current_pages;
+ balloon_stats.target_pages = balloon_stats.current_pages;
+ return BP_DONE;
}
+#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */

-static bool balloon_is_inflated(void)
+static long current_credit(void)
{
- if (balloon_stats.balloon_low || balloon_stats.balloon_high)
- return true;
- else
- return false;
+ return balloon_stats.target_pages - balloon_stats.current_pages;
}

-static enum bp_state reserve_additional_memory(long credit)
+static bool balloon_is_inflated(void)
{
- balloon_stats.target_pages = balloon_stats.current_pages;
- return BP_DONE;
+ return balloon_stats.balloon_low || balloon_stats.balloon_high;
}
-#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */

static enum bp_state increase_reservation(unsigned long nr_pages)
{
@@ -367,15 +334,6 @@ static enum bp_state increase_reservation(unsigned long nr_pages)
.domid = DOMID_SELF
};

-#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
- if (!balloon_stats.balloon_low && !balloon_stats.balloon_high) {
- nr_pages = min(nr_pages, balloon_stats.balloon_hotplug);
- balloon_stats.hotplug_pages += nr_pages;
- balloon_stats.balloon_hotplug -= nr_pages;
- return BP_DONE;
- }
-#endif
-
if (nr_pages > ARRAY_SIZE(frame_list))
nr_pages = ARRAY_SIZE(frame_list);

@@ -438,15 +396,6 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
.domid = DOMID_SELF
};

-#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
- if (balloon_stats.hotplug_pages) {
- nr_pages = min(nr_pages, balloon_stats.hotplug_pages);
- balloon_stats.hotplug_pages -= nr_pages;
- balloon_stats.balloon_hotplug += nr_pages;
- return BP_DONE;
- }
-#endif
-
if (nr_pages > ARRAY_SIZE(frame_list))
nr_pages = ARRAY_SIZE(frame_list);

@@ -636,6 +585,8 @@ static void __init balloon_add_region(unsigned long start_pfn,
don't subtract from it. */
__balloon_append(page);
}
+
+ balloon_stats.total_pages += extra_pfn_end - start_pfn;
}

static int __init balloon_init(void)
@@ -653,6 +604,7 @@ static int __init balloon_init(void)
balloon_stats.target_pages = balloon_stats.current_pages;
balloon_stats.balloon_low = 0;
balloon_stats.balloon_high = 0;
+ balloon_stats.total_pages = balloon_stats.current_pages;

balloon_stats.schedule_delay = 1;
balloon_stats.max_schedule_delay = 32;
@@ -660,9 +612,6 @@ static int __init balloon_init(void)
balloon_stats.max_retry_count = RETRY_UNLIMITED;

#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
- balloon_stats.hotplug_pages = 0;
- balloon_stats.balloon_hotplug = 0;
-
set_online_page_callback(&xen_online_page);
register_memory_notifier(&xen_memory_nb);
#endif
diff --git a/include/xen/balloon.h b/include/xen/balloon.h
index cc2e1a7..c8aee7a 100644
--- a/include/xen/balloon.h
+++ b/include/xen/balloon.h
@@ -11,14 +11,11 @@ struct balloon_stats {
/* Number of pages in high- and low-memory balloons. */
unsigned long balloon_low;
unsigned long balloon_high;
+ unsigned long total_pages;
unsigned long schedule_delay;
unsigned long max_schedule_delay;
unsigned long retry_count;
unsigned long max_retry_count;
-#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
- unsigned long hotplug_pages;
- unsigned long balloon_hotplug;
-#endif
};

extern struct balloon_stats balloon_stats;
--
2.1.4


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