• Artem Bityutskiy's avatar
    sunrpc: make the cache cleaner workqueue deferrable · 8eab945c
    Artem Bityutskiy authored
    This patch makes the cache_cleaner workqueue deferrable, to prevent
    unnecessary system wake-ups, which is very important for embedded
    battery-powered devices.
    
    do_cache_clean() is called every 30 seconds at the moment, and often
    makes the system wake up from its power-save sleep state. With this
    change, when the workqueue uses a deferrable timer, the
    do_cache_clean() invocation will be delayed and combined with the
    closest "real" wake-up. This improves the power consumption situation.
    
    Note, I tried to create a DECLARE_DELAYED_WORK_DEFERRABLE() helper
    macro, similar to DECLARE_DELAYED_WORK(), but failed because of the
    way the timer wheel core stores the deferrable flag (it is the
    LSBit in the time->base pointer). My attempt to define a static
    variable with this bit set ended up with the "initializer element is
    not constant" error.
    
    Thus, I have to use run-time initialization, so I created a new
    cache_initialize() function which is called once when sunrpc is
    being initialized.
    Signed-off-by: default avatarArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
    Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
    8eab945c
cache.c 39.7 KB