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From: "K. Y. Srinivasan" <kys@microsoft.com>
To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
	devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com,
	vkuznets@redhat.com, jasowang@redhat.com
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Subject: [PATCH 5/7] Drivers: hv: hv_balloon: eliminate jumps in piecewiese linear floor function
Date: Fri, 27 Mar 2015 09:10:12 -0700	[thread overview]
Message-ID: <1427472614-32625-5-git-send-email-kys@microsoft.com> (raw)
In-Reply-To: <1427472614-32625-1-git-send-email-kys@microsoft.com>

From: Vitaly Kuznetsov <vkuznets@redhat.com>

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@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/hv_balloon.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 99afef9..4f5323c 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -976,8 +976,8 @@ 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);
@@ -986,9 +986,9 @@ 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;
 }
-- 
1.7.4.1


  parent reply	other threads:[~2015-03-27 14:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-27 16:09 [PATCH 0/7] Drivers: hv: Miscellaneous cleanups and bug fixes K. Y. Srinivasan
2015-03-27 16:10 ` [PATCH 1/7] hv: run non-blocking message handlers in the dispatch tasklet K. Y. Srinivasan
2015-03-27 16:10   ` [PATCH 2/7] hv: don't schedule new works in vmbus_onoffer()/vmbus_onoffer_rescind() K. Y. Srinivasan
2015-03-27 16:10   ` [PATCH 3/7] hv: remove the per-channel workqueue K. Y. Srinivasan
2015-03-27 16:10   ` [PATCH 4/7] Drivers: hv: hv_balloon: do not online pages in offline blocks K. Y. Srinivasan
2015-03-27 16:10   ` K. Y. Srinivasan [this message]
2015-03-27 16:10   ` [PATCH 6/7] Drivers: hv: hv_balloon: survive ballooning request with num_pages=0 K. Y. Srinivasan
2015-03-27 16:10   ` [PATCH 7/7] hv_vmbus: Add gradually increased delay for retries in vmbus_post_msg() K. Y. Srinivasan

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