[PATCH] swsusp: make image size limit tunable

Make the suspend image size limit tunable via /sys/power/image_size.

It is necessary for systems on which there is a limited amount of swap
available for suspend.  It can also be useful for optimizing performance of
swsusp on systems with 1 GB of RAM or more.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/Documentation/power/interface.txt b/Documentation/power/interface.txt
index f5ebda5..bd4ffb5 100644 (file)
--- a/Documentation/power/interface.txt
+++ b/Documentation/power/interface.txt
@@ -41,3 +41,14 @@ to. Writing to this file will accept one of
 It will only change to 'firmware' or 'platform' if the system supports
 it. 
 
 It will only change to 'firmware' or 'platform' if the system supports
 it. 
 

+/sys/power/image_size controls the size of the image created by
+the suspend-to-disk mechanism.  It can be written a string
+representing a non-negative integer that will be used as an upper
+limit of the image size, in megabytes.  The suspend-to-disk mechanism will
+do its best to ensure the image size will not exceed that number.  However,
+if this turns out to be impossible, it will try to suspend anyway using the
+smallest image possible.  In particular, if "0" is written to this file, the
+suspend image will be as small as possible.
+
+Reading from this file will display the current image size limit, which
+is set to 500 MB by default.

diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt
index b0d5084..cd0fcd8 100644 (file)
--- a/Documentation/power/swsusp.txt
+++ b/Documentation/power/swsusp.txt
@@ -27,6 +27,11 @@ echo shutdown > /sys/power/disk; echo disk > /sys/power/state
 
 echo platform > /sys/power/disk; echo disk > /sys/power/state
 
 
 echo platform > /sys/power/disk; echo disk > /sys/power/state
 

+If you want to limit the suspend image size to N megabytes, do
+
+echo N > /sys/power/image_size
+
+before suspend (it is limited to 500 MB by default).

 
 Encrypted suspend image:
 ------------------------
 
 Encrypted suspend image:
 ------------------------

diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index 9e51cdf..e24446f 100644 (file)
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -365,9 +365,29 @@ out:
 
 power_attr(resume);
 
 
 power_attr(resume);
 

+static ssize_t image_size_show(struct subsystem * subsys, char *buf)
+{
+       return sprintf(buf, "%u\n", image_size);
+}
+
+static ssize_t image_size_store(struct subsystem * subsys, const char * buf, size_t n)
+{
+       unsigned int size;
+
+       if (sscanf(buf, "%u", &size) == 1) {
+               image_size = size;
+               return n;
+       }
+
+       return -EINVAL;
+}
+
+power_attr(image_size);
+

 static struct attribute * g[] = {
        &disk_attr.attr,
        &resume_attr.attr,
 static struct attribute * g[] = {
        &disk_attr.attr,
        &resume_attr.attr,

+       &image_size_attr.attr,

        NULL,
 };
 
        NULL,
 };
 

diff --git a/kernel/power/power.h b/kernel/power/power.h
index 9b04599..273a5b1 100644 (file)
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -52,11 +52,8 @@ extern const void __nosave_begin, __nosave_end;
 extern unsigned int nr_copy_pages;
 extern struct pbe *pagedir_nosave;
 
 extern unsigned int nr_copy_pages;
 extern struct pbe *pagedir_nosave;
 

-/*
- * Preferred image size in MB (set it to zero to get the smallest
- * image possible)
- */
-#define IMAGE_SIZE     500
+/* Preferred image size in MB (default 500) */
+extern unsigned int image_size;

 
 extern asmlinkage int swsusp_arch_suspend(void);
 extern asmlinkage int swsusp_arch_resume(void);
 
 extern asmlinkage int swsusp_arch_suspend(void);
 extern asmlinkage int swsusp_arch_resume(void);

diff --git a/kernel/power/swsusp.c b/kernel/power/swsusp.c
index 6d5ceaf..d760a6a 100644 (file)
--- a/kernel/power/swsusp.c
+++ b/kernel/power/swsusp.c
@@ -69,6 +69,14 @@
 
 #include "power.h"
 
 
 #include "power.h"
 

+/*
+ * Preferred image size in MB (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 MB, but if that is impossible, it will
+ * try to create the smallest image possible.
+ */
+unsigned int image_size = 500;
+

 #ifdef CONFIG_HIGHMEM
 unsigned int count_highmem_pages(void);
 int save_highmem(void);
 #ifdef CONFIG_HIGHMEM
 unsigned int count_highmem_pages(void);
 int save_highmem(void);


@@ -647,7 +655,7 @@ int swsusp_shrink_memory(void)
                        if (!tmp)
                                return -ENOMEM;
                        pages += tmp;
                        if (!tmp)
                                return -ENOMEM;
                        pages += tmp;

-               } else if (size > (IMAGE_SIZE * 1024 * 1024) / PAGE_SIZE) {
+               } else if (size > (image_size * 1024 * 1024) / PAGE_SIZE) {

                        tmp = shrink_all_memory(SHRINK_BITE);
                        pages += tmp;
                }
                        tmp = shrink_all_memory(SHRINK_BITE);
                        pages += tmp;
                }