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    SubjectRe: [RFC/RFT] swsusp: image size tunable (was: Re: [PATCH][mm] swsusp: limit image size)
    Date
    Update:

    On Saturday, 10 December 2005 21:06, Rafael J. Wysocki wrote:
    > On Saturday, 10 December 2005 17:06, Pavel Machek wrote:
    > > > > The tunable may be useful to people who'd like to achieve the
    > > > > maximum efficiency of suspend/resume and it would be a nice
    > > > > feature to have, I think, but let's say we'll try to implement it
    > > > > in the future, if still needed/wanted.
    > > >
    > > > Actually the tunable turned out to be quite easy to implement and I think
    > > > I'll need it for userspace swsusp (the suspend-handling userspace
    > > > process will need to tell the kernel how much space there is for the
    > > > image).
    > >
    > > Looks mostly okay to me, small comments below.

    A cleaner version with comments etc. follows.

    Rafael


    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

    Documentation/power/interface.txt | 11 +++++++++++
    Documentation/power/swsusp.txt | 7 ++++++-
    kernel/power/disk.c | 20 ++++++++++++++++++++
    kernel/power/power.h | 7 ++-----
    kernel/power/swsusp.c | 10 +++++++++-
    5 files changed, 48 insertions(+), 7 deletions(-)

    Index: linux-2.6.15-rc5-mm1/kernel/power/disk.c
    ===================================================================
    --- linux-2.6.15-rc5-mm1.orig/kernel/power/disk.c 2005-12-07 23:19:03.000000000 +0100
    +++ linux-2.6.15-rc5-mm1/kernel/power/disk.c 2005-12-10 21:10:53.000000000 +0100
    @@ -367,9 +367,29 @@

    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,
    + &image_size_attr.attr,
    NULL,
    };

    Index: linux-2.6.15-rc5-mm1/kernel/power/power.h
    ===================================================================
    --- linux-2.6.15-rc5-mm1.orig/kernel/power/power.h 2005-12-10 20:59:52.000000000 +0100
    +++ linux-2.6.15-rc5-mm1/kernel/power/power.h 2005-12-10 21:13:04.000000000 +0100
    @@ -52,11 +52,8 @@
    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);
    Index: linux-2.6.15-rc5-mm1/kernel/power/swsusp.c
    ===================================================================
    --- linux-2.6.15-rc5-mm1.orig/kernel/power/swsusp.c 2005-12-10 20:59:52.000000000 +0100
    +++ linux-2.6.15-rc5-mm1/kernel/power/swsusp.c 2005-12-10 22:21:25.000000000 +0100
    @@ -69,6 +69,14 @@

    #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);
    @@ -647,7 +655,7 @@
    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;
    }
    Index: linux-2.6.15-rc5-mm1/Documentation/power/swsusp.txt
    ===================================================================
    --- linux-2.6.15-rc5-mm1.orig/Documentation/power/swsusp.txt 2005-10-28 02:02:08.000000000 +0200
    +++ linux-2.6.15-rc5-mm1/Documentation/power/swsusp.txt 2005-12-10 23:49:08.000000000 +0100
    @@ -27,6 +27,11 @@

    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:
    ------------------------
    Index: linux-2.6.15-rc5-mm1/Documentation/power/interface.txt
    ===================================================================
    --- linux-2.6.15-rc5-mm1.orig/Documentation/power/interface.txt 2005-10-28 02:02:08.000000000 +0200
    +++ linux-2.6.15-rc5-mm1/Documentation/power/interface.txt 2005-12-10 23:42:39.000000000 +0100
    @@ -41,3 +41,14 @@
    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.
    -
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