linux-kernel - [PATCH] PM / Hibernate: Reduce autotuned default image size

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Message-Id: <201103150042.23288.rjw@sisk.pl>
Date:	Tue, 15 Mar 2011 00:42:23 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Martin Steigerwald <Martin@...htvoll.de>
Subject: [PATCH] PM / Hibernate: Reduce autotuned default image size

From: Rafael J. Wysocki <rjw@...k.pl>

The hibernate image size autotuning mechanism sets the default
image size to 5/2 of the total system RAM, but it is reported
that on some systems device drivers allocate substantial
amounts of memory during suspend and the creation of the image
fails as a result (too little memory is preallocated).

Modify the autotuning mechanism to use 1/3 instead of 2/5 of RAM
as the default image size, which is reported to be sufficient for
the affected systems.

References: https://bugzilla.kernel.org/show_bug.cgi?id=30482
Reported-and-tested-by: Martin Steigerwald <Martin@...htvoll.de>
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
 kernel/power/snapshot.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Index: linux-2.6/kernel/power/snapshot.c
===================================================================
--- linux-2.6.orig/kernel/power/snapshot.c
+++ linux-2.6/kernel/power/snapshot.c
@@ -42,15 +42,15 @@ static void swsusp_unset_page_forbidden(
 
 /*
  * Preferred image size in bytes (tunable via /sys/power/image_size).
- * When it is set to N, swsusp will do its best to ensure the image
- * size will not exceed N bytes, but if that is impossible, it will
- * try to create the smallest image possible.
+ * When it is set to N, the image creating code will do its best to
+ * ensure the image size will not exceed N bytes, but if that is
+ * impossible, it will try to create the smallest image possible.
  */
 unsigned long image_size;
 
 void __init hibernate_image_size_init(void)
 {
-	image_size = ((totalram_pages * 2) / 5) * PAGE_SIZE;
+	image_size = (totalram_pages / 3) * PAGE_SIZE;
 }
 
 /* List of PBEs needed for restoring the pages that were allocated before
--
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