• Rafael J. Wysocki's avatar
    PM / Hibernate: Add sysfs knob to control size of memory for drivers · ddeb6487
    Rafael J. Wysocki authored
    Martin reports that on his system hibernation occasionally fails due
    to the lack of memory, because the radeon driver apparently allocates
    too much of it during the device freeze stage.  It turns out that the
    amount of memory allocated by radeon during hibernation (and
    presumably during system suspend too) depends on the utilization of
    the GPU (e.g. hibernating while there are two KDE 4 sessions with
    compositing enabled causes radeon to allocate more memory than for
    one KDE 4 session).
    
    In principle it should be possible to use image_size to make the
    memory preallocation mechanism free enough memory for the radeon
    driver, but in practice it is not easy to guess the right value
    because of the way the preallocation code uses image_size.  For this
    reason, it seems reasonable to allow users to control the amount of
    memory reserved for driver allocations made after the hibernate
    preallocation, which currently is constant and amounts to 1 MB.
    
    Introduce a new sysfs file, /sys/power/reserved_size, whose value
    will be used as the amount of memory to reserve for the
    post-preallocation reservations made by device drivers, in bytes.
    For backwards compatibility, set its default (and initial) value to
    the currently used number (1 MB).
    
    References: https://bugzilla.kernel.org/show_bug.cgi?id=34102Reported-and-tested-by: default avatarMartin Steigerwald <Martin@Lichtvoll.de>
    Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
    ddeb6487
sysfs-power 7.24 KB