Based on the amount of memory being managed set a floor on how low the
guest can be ballooned.
Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
Reviewed-by: Haiyang Zhang <haiya...@microsoft.com>
---
drivers/hv/hv_balloon.c | 35 ++++++++++++++++++++++++++++++++++-
1 files changed, 34 insertions(+), 1 deletions(-)
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index f8fc996..3787321 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -523,6 +523,34 @@ static void process_info(struct hv_dynmem_device *dm,
struct dm_info_msg *msg)
}
}
+unsigned long compute_balloon_floor(void)
+{
+ unsigned long min_pages;
+#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
+ /* Simple continuous piecewiese linear function:
+ * max MiB -> min MiB gradient
+ * 0 0
+ * 16 16
+ * 32 24
+ * 128 72 (1/2)
+ * 512 168 (1/4)
+ * 2048 360 (1/8)
+ * 8192 552 (1/32)
+ * 32768 1320
+ * 131072 4392
+ */
+ if (totalram_pages < MB2PAGES(128))
+ min_pages = MB2PAGES(8) + (totalram_pages >> 1);
+ else if (totalram_pages < MB2PAGES(512))
+ min_pages = MB2PAGES(40) + (totalram_pages >> 2);
+ else if (totalram_pages < MB2PAGES(2048))
+ min_pages = MB2PAGES(104) + (totalram_pages >> 3);
+ else
+ min_pages = MB2PAGES(296) + (totalram_pages >> 5);
+#undef MB2PAGES
+ return min_pages;
+}
+
/*
* Post our status as it relates memory pressure to the
* host. Host expects the guests to post this status
@@ -552,9 +580,14 @@ static void post_status(struct hv_dynmem_device *dm)
* The host expects the guest to report free memory.
* Further, the host expects the pressure information to
* include the ballooned out pages.
+ * For a given amount of memory that we are managing, we
+ * need to compute a floor below which we should not balloon.
+ * Compute this and add it to the pressure report.
*/
status.num_avail = val.freeram;
- status.num_committed = vm_memory_committed() + dm->num_pages_ballooned;
+ status.num_committed = vm_memory_committed() +
+ dm->num_pages_ballooned +
+ compute_balloon_floor();
vmbus_sendpacket(dm->dev->channel, &status,
sizeof(struct dm_status),
--
1.7.4.1
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