[PATCH] Drivers: hv: hv_balloon: eliminate jumps in piecewiese linear floor function

From: Vitaly Kuznetsov
Date: Thu Mar 26 2015 - 06:27:07 EST


Commit 79208c57da53 ("Drivers: hv: hv_balloon: Make adjustments in computing
the floor") was inacurate as it introduced a jump in our piecewiese linear
'floor' function:

At 2048MB we have:
Left limit:
104 + 2048/8 = 360
Right limit:
256 + 2048/16 = 384 (so the right value is 232)

We now have to make an adjustment at 8192 boundary:
232 + 8192/16 = 744
512 + 8192/32 = 768 (so the right value is 488)

Suggested-by: Laszlo Ersek <lersek@xxxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
drivers/hv/hv_balloon.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 014256a..16d52da 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -966,8 +966,8 @@ static unsigned long compute_balloon_floor(void)
* 128 72 (1/2)
* 512 168 (1/4)
* 2048 360 (1/8)
- * 8192 768 (1/16)
- * 32768 1536 (1/32)
+ * 8192 744 (1/16)
+ * 32768 1512 (1/32)
*/
if (totalram_pages < MB2PAGES(128))
min_pages = MB2PAGES(8) + (totalram_pages >> 1);
@@ -976,9 +976,9 @@ static unsigned long compute_balloon_floor(void)
else if (totalram_pages < MB2PAGES(2048))
min_pages = MB2PAGES(104) + (totalram_pages >> 3);
else if (totalram_pages < MB2PAGES(8192))
- min_pages = MB2PAGES(256) + (totalram_pages >> 4);
+ min_pages = MB2PAGES(232) + (totalram_pages >> 4);
else
- min_pages = MB2PAGES(512) + (totalram_pages >> 5);
+ min_pages = MB2PAGES(488) + (totalram_pages >> 5);
#undef MB2PAGES
return min_pages;
}
--
1.9.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/