The required change in the balloon size is currently computed in
vmballoon_work(), vmballoon_inflate() and vmballoon_deflate(). Refactor
it to simplify the next patches.
Reviewed-by: Xavier Deguillard <xdeguill...@vmware.com>
Signed-off-by: Nadav Amit <na...@vmware.com>
---
drivers/misc/vmw_balloon.c | 74 ++++++++++++++++++++++++++------------
1 file changed, 51 insertions(+), 23 deletions(-)
diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index 74fff1e314a7..aafd087809e9 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -632,6 +632,36 @@ static void vmballoon_add_page(struct vmballoon *b, int
idx, struct page *p)
b->page = p;
}
+/**
+ * vmballoon_change - retrieve the required balloon change
+ *
+ * @b: pointer for the balloon.
+ *
+ * Return: the required change for the balloon size. A positive number
+ * indicates inflation, a negative number indicates a deflation.
+ */
+static int64_t vmballoon_change(struct vmballoon *b)
+{
+ int64_t size, target;
+
+ size = b->size;
+ target = b->target;
+
+ /*
+ * We must cast first because of int sizes
+ * Otherwise we might get huge positives instead of negatives
+ */
+
+ if (b->reset_required)
+ return 0;
+
+ /* consider a 2MB slack on deflate, unless the balloon is emptied */
+ if (target < size && size - target < HPAGE_PMD_NR && target != 0)
+ return 0;
+
+ return target - size;
+}
+
/*
* Inflate the balloon towards its target size. Note that we try to limit
* the rate of allocation to make sure we are not choking the rest of the
@@ -643,8 +673,6 @@ static void vmballoon_inflate(struct vmballoon *b)
int error = 0;
bool is_2m_pages;
- pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
-
/*
* First try NOSLEEP page allocations to inflate balloon.
*
@@ -666,11 +694,8 @@ static void vmballoon_inflate(struct vmballoon *b)
*/
is_2m_pages = b->supported_page_sizes == VMW_BALLOON_NUM_PAGE_SIZES;
- pr_debug("%s - goal: %d", __func__, b->target - b->size);
-
- while (!b->reset_required &&
- b->size + num_pages * vmballoon_page_size(is_2m_pages)
- < b->target) {
+ while ((int64_t)(num_pages * vmballoon_page_size(is_2m_pages)) <
+ vmballoon_change(b)) {
struct page *page;
STATS_INC(b->stats.alloc[is_2m_pages]);
@@ -741,8 +766,6 @@ static void vmballoon_deflate(struct vmballoon *b)
{
unsigned is_2m_pages;
- pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
-
/* free pages to reach target */
for (is_2m_pages = 0; is_2m_pages < b->supported_page_sizes;
is_2m_pages++) {
@@ -752,11 +775,9 @@ static void vmballoon_deflate(struct vmballoon *b)
&b->page_sizes[is_2m_pages];
list_for_each_entry_safe(page, next, &page_size->pages, lru) {
- if (b->reset_required ||
- (b->target > 0 &&
- b->size - num_pages
- * vmballoon_page_size(is_2m_pages)
- < b->target + vmballoon_page_size(true)))
+ if ((int64_t)(num_pages *
+ vmballoon_page_size(is_2m_pages)) >=
+ -vmballoon_change(b))
break;
list_del(&page->lru);
@@ -920,28 +941,35 @@ static void vmballoon_reset(struct vmballoon *b)
pr_err("failed to send guest ID to the host\n");
}
-/*
- * Balloon work function: reset protocol, if needed, get the new size and
- * adjust balloon as needed. Repeat in 1 sec.
+/**
+ * vmballoon_work - periodic balloon worker for reset, inflation and deflation.
+ *
+ * @work: pointer to the &work_struct which is provided by the workqueue.
+ *
+ * Resets the protocol if needed, gets the new size and adjusts balloon as
+ * needed. Repeat in 1 sec.
*/
static void vmballoon_work(struct work_struct *work)
{
struct delayed_work *dwork = to_delayed_work(work);
struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
+ int64_t change = 0;
STATS_INC(b->stats.timer);
if (b->reset_required)
vmballoon_reset(b);
- if (!b->reset_required && vmballoon_send_get_target(b)) {
- unsigned long target = b->target;
+ if (vmballoon_send_get_target(b))
+ change = vmballoon_change(b);
+
+ if (change != 0) {
+ pr_debug("%s - size: %u, target %u", __func__,
+ b->size, b->target);
- /* update target, adjust size */
- if (b->size < target)
+ if (change > 0)
vmballoon_inflate(b);
- else if (target == 0 ||
- b->size > target + vmballoon_page_size(true))
+ else /* (change < 0) */
vmballoon_deflate(b);
}
--
2.17.1
