On Thu, Apr 15, 2010 at 06:21:39PM +0100, Mel Gorman wrote:
> shrink_zone() calculculates how many pages it needs to shrink from each
> LRU list in a given pass. It uses a number of temporary variables to
> work this out that then remain on the stack. This patch splits the
> function so that some of the stack variables can be discarded.
>
> Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
> ---
> mm/vmscan.c | 29 +++++++++++++++++++----------
> 1 files changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 1ace7c6..a374879 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1595,19 +1595,14 @@ static unsigned long nr_scan_try_batch(unsigned long nr_to_scan,
> return nr;
> }
>
> -/*
> - * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
> - */
> -static void shrink_zone(struct zone *zone, struct scan_control *sc)
> +/* Calculate how many pages from each LRU list should be scanned */
> +static void calc_scan_trybatch(struct zone *zone,
> + struct scan_control *sc, unsigned long *nr)
> {
> - unsigned long nr[NR_LRU_LISTS];
> - unsigned long nr_to_scan;
> - unsigned long percent[2]; /* anon @ 0; file @ 1 */
> enum lru_list l;
> - unsigned long nr_reclaimed = sc->nr_reclaimed;
> - unsigned long nr_to_reclaim = sc->nr_to_reclaim;
> + unsigned long percent[2]; /* anon @ 0; file @ 1 */
> + int noswap = 0 ;
> struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
> - int noswap = 0;
>
> /* If we have no swap space, do not bother scanning anon pages. */
> if (!sc->may_swap || (nr_swap_pages <= 0)) {
> @@ -1629,6 +1624,20 @@ static void shrink_zone(struct zone *zone, struct scan_control *sc)
> nr[l] = nr_scan_try_batch(scan,
> &reclaim_stat->nr_saved_scan[l]);
> }
> +}
> +
> +/*
> + * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
> + */
> +static void shrink_zone(struct zone *zone, struct scan_control *sc)
> +{
> + unsigned long nr[NR_LRU_LISTS];
> + unsigned long nr_to_scan;
> + unsigned long nr_reclaimed = sc->nr_reclaimed;
> + unsigned long nr_to_reclaim = sc->nr_to_reclaim;
> + enum lru_list l;
> +
> + calc_scan_trybatch(zone, sc, nr);
Uh, that does not sound very nice! How about calculate_scan_work() or
something like that? Might as well use the function to abstract detail :)
Other than that (and with the noinline_for_stack):
Reviewed-by: Johannes Weiner <hannes@xxxxxxxxxxx>
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