[2/2] PM / Hibernate: Make default image size depend on total RAM size

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

The default hibernation image size is currently hard coded and euqal
to 500 MB, which is not a reasonable default on many contemporary
systems.  Make it equal 2/5 of the total RAM size (this is slightly
below the maximum, i.e. 1/2 of the total RAM size, and seems to be
generally suitable).

BugLink: http://launchpad.net/bugs/737208

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: M. Vefa Bicakci <bicave@superonline.com>
(cherry picked from commit ac5c24ec1e983313ef0015258fba6f630e54e7cf)

Signed-off-by: Manoj Iyer <manoj.iyer@canonical.com>
---
 Documentation/power/interface.txt |    2 +-
 kernel/power/main.c               |    1 +
 kernel/power/power.h              |    9 ++++++++-
 kernel/power/snapshot.c           |    7 ++++++-
 4 files changed, 16 insertions(+), 3 deletions(-)

On 03/18/2011 05:22 PM, Manoj Iyer wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
> 
> The default hibernation image size is currently hard coded and euqal
> to 500 MB, which is not a reasonable default on many contemporary
> systems.  Make it equal 2/5 of the total RAM size (this is slightly
> below the maximum, i.e. 1/2 of the total RAM size, and seems to be
> generally suitable).
> 
> BugLink: http://launchpad.net/bugs/737208
> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> Tested-by: M. Vefa Bicakci <bicave@superonline.com>
> (cherry picked from commit ac5c24ec1e983313ef0015258fba6f630e54e7cf)
> 
> Signed-off-by: Manoj Iyer <manoj.iyer@canonical.com>
> ---
>  Documentation/power/interface.txt |    2 +-
>  kernel/power/main.c               |    1 +
>  kernel/power/power.h              |    9 ++++++++-
>  kernel/power/snapshot.c           |    7 ++++++-
>  4 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/power/interface.txt b/Documentation/power/interface.txt
> index e67211f..c537834 100644
> --- a/Documentation/power/interface.txt
> +++ b/Documentation/power/interface.txt
> @@ -57,7 +57,7 @@ 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.
> +is set to 2/5 of available RAM by default.
>  
>  /sys/power/pm_trace controls the code which saves the last PM event point in
>  the RTC across reboots, so that you can debug a machine that just hangs
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index b58800b..51e2643 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -266,6 +266,7 @@ static int __init pm_init(void)
>  	int error = pm_start_workqueue();
>  	if (error)
>  		return error;
> +	hibernate_image_size_init();
>  	power_kobj = kobject_create_and_add("power", NULL);
>  	if (!power_kobj)
>  		return -ENOMEM;
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index 006270f..54580cb 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -14,6 +14,9 @@ struct swsusp_info {
>  } __attribute__((aligned(PAGE_SIZE)));
>  
>  #ifdef CONFIG_HIBERNATION
> +/* kernel/power/snapshot.c */
> +extern void __init hibernate_image_size_init(void);
> +
>  #ifdef CONFIG_ARCH_HIBERNATION_HEADER
>  /* Maximum size of architecture specific data in a hibernation header */
>  #define MAX_ARCH_HEADER_SIZE	(sizeof(struct new_utsname) + 4)
> @@ -49,7 +52,11 @@ static inline char *check_image_kernel(struct swsusp_info *info)
>  extern int hibernation_snapshot(int platform_mode);
>  extern int hibernation_restore(int platform_mode);
>  extern int hibernation_platform_enter(void);
> -#endif
> +
> +#else /* !CONFIG_HIBERNATION */
> +
> +static inline void hibernate_image_size_init(void) {}
> +#endif /* !CONFIG_HIBERNATION */
>  
>  extern int pfn_is_nosave(unsigned long);
>  
> diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> index 703a057..a64e9db 100644
> --- a/kernel/power/snapshot.c
> +++ b/kernel/power/snapshot.c
> @@ -46,7 +46,12 @@ static void swsusp_unset_page_forbidden(struct page *);
>   * size will not exceed N bytes, but if that is impossible, it will
>   * try to create the smallest image possible.
>   */
> -unsigned long image_size = 500 * 1024 * 1024;
> +unsigned long image_size;
> +
> +void __init hibernate_image_size_init(void)
> +{
> +	image_size = ((totalram_pages * 2) / 5) * PAGE_SIZE;
> +}
>  
>  /* List of PBEs needed for restoring the pages that were allocated before
>   * the suspend and included in the suspend image, but have also been

Look reasonably safe.

Acked-by: Stefan Bader <stefan.bader@canonical.com>