本文共 1137 字，大约阅读时间需要 3 分钟。

/*

 * kswapd shrinks the zone by the number ofpages required to reach

 * the high watermark.

 *

 * Returns true if kswapd scanned at least therequested number of pages to

 * reclaim or if the lack of progress was dueto pages under writeback.

 * This is used to determine if the scanningpriority needs to be raised.

 */

static bool kswapd_shrink_zone(struct zone *zone,intclasszone_idx,struct

                                          scan_control*sc)

{

       unsigned long balance_gap;

       bool lowmem_pressure;

       /* Reclaim above the high watermark. */

       sc->nr_to_reclaim =max(SWAP_CLUSTER_MAX, high_wmark_pages(zone));

       balance_gap = min(low_wmark_pages(zone),

                                          DIV_ROUND_UP(zone->managed_pages,

                                                                             KSWAPD_ZONE_BALANCE_GAP_RATIO));

       lowmem_pressure =(buffer_heads_over_limit && is_highmem(zone));

       if (!lowmem_pressure && zone_balanced(zone,sc->order, false,balance_gap,

                                   classzone_idx))

              return true;

       shrink_zone(zone, sc,zone_idx(zone) == classzone_idx);

       clear_bit(ZONE_WRITEBACK,&zone->flags);

       if (zone_reclaimable(zone) &&zone_balanced(zone, sc->order, false, 0,

                                   classzone_idx)){

              clear_bit(ZONE_CONGESTED,&zone->flags);

              clear_bit(ZONE_DIRTY,&zone->flags);

       }

       return sc->nr_scanned >=sc->nr_to_reclaim;

}

转载地址：http://rxqti.baihongyu.com/