From 0608f43da64a1f1c42507304b5f25bc8b1227aa4 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Tue, 24 Sep 2013 15:27:41 -0700 Subject: revert "memcg, vmscan: integrate soft reclaim tighter with zone shrinking code" Revert commit 3b38722efd9f ("memcg, vmscan: integrate soft reclaim tighter with zone shrinking code") I merged this prematurely - Michal and Johannes still disagree about the overall design direction and the future remains unclear. Cc: Michal Hocko Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 163 ++++++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 142 insertions(+), 21 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 852dbec07ce6..1c52ddbc839b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1991,28 +1991,57 @@ static bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap) } #endif -/* - * A group is eligible for the soft limit reclaim if - * a) it is over its soft limit - * b) any parent up the hierarchy is over its soft limit - */ -bool mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg) -{ - struct mem_cgroup *parent = memcg; - - if (res_counter_soft_limit_excess(&memcg->res)) - return true; - - /* - * If any parent up the hierarchy is over its soft limit then we - * have to obey and reclaim from this group as well. - */ - while ((parent = parent_mem_cgroup(parent))) { - if (res_counter_soft_limit_excess(&parent->res)) - return true; +static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg, + struct zone *zone, + gfp_t gfp_mask, + unsigned long *total_scanned) +{ + struct mem_cgroup *victim = NULL; + int total = 0; + int loop = 0; + unsigned long excess; + unsigned long nr_scanned; + struct mem_cgroup_reclaim_cookie reclaim = { + .zone = zone, + .priority = 0, + }; + + excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT; + + while (1) { + victim = mem_cgroup_iter(root_memcg, victim, &reclaim); + if (!victim) { + loop++; + if (loop >= 2) { + /* + * If we have not been able to reclaim + * anything, it might because there are + * no reclaimable pages under this hierarchy + */ + if (!total) + break; + /* + * We want to do more targeted reclaim. + * excess >> 2 is not to excessive so as to + * reclaim too much, nor too less that we keep + * coming back to reclaim from this cgroup + */ + if (total >= (excess >> 2) || + (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) + break; + } + continue; + } + if (!mem_cgroup_reclaimable(victim, false)) + continue; + total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false, + zone, &nr_scanned); + *total_scanned += nr_scanned; + if (!res_counter_soft_limit_excess(&root_memcg->res)) + break; } - - return false; + mem_cgroup_iter_break(root_memcg, victim); + return total; } static DEFINE_SPINLOCK(memcg_oom_lock); @@ -4761,6 +4790,98 @@ static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg, return ret; } +unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, + gfp_t gfp_mask, + unsigned long *total_scanned) +{ + unsigned long nr_reclaimed = 0; + struct mem_cgroup_per_zone *mz, *next_mz = NULL; + unsigned long reclaimed; + int loop = 0; + struct mem_cgroup_tree_per_zone *mctz; + unsigned long long excess; + unsigned long nr_scanned; + + if (order > 0) + return 0; + + mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone)); + /* + * This loop can run a while, specially if mem_cgroup's continuously + * keep exceeding their soft limit and putting the system under + * pressure + */ + do { + if (next_mz) + mz = next_mz; + else + mz = mem_cgroup_largest_soft_limit_node(mctz); + if (!mz) + break; + + nr_scanned = 0; + reclaimed = mem_cgroup_soft_reclaim(mz->memcg, zone, + gfp_mask, &nr_scanned); + nr_reclaimed += reclaimed; + *total_scanned += nr_scanned; + spin_lock(&mctz->lock); + + /* + * If we failed to reclaim anything from this memory cgroup + * it is time to move on to the next cgroup + */ + next_mz = NULL; + if (!reclaimed) { + do { + /* + * Loop until we find yet another one. + * + * By the time we get the soft_limit lock + * again, someone might have aded the + * group back on the RB tree. Iterate to + * make sure we get a different mem. + * mem_cgroup_largest_soft_limit_node returns + * NULL if no other cgroup is present on + * the tree + */ + next_mz = + __mem_cgroup_largest_soft_limit_node(mctz); + if (next_mz == mz) + css_put(&next_mz->memcg->css); + else /* next_mz == NULL or other memcg */ + break; + } while (1); + } + __mem_cgroup_remove_exceeded(mz->memcg, mz, mctz); + excess = res_counter_soft_limit_excess(&mz->memcg->res); + /* + * One school of thought says that we should not add + * back the node to the tree if reclaim returns 0. + * But our reclaim could return 0, simply because due + * to priority we are exposing a smaller subset of + * memory to reclaim from. Consider this as a longer + * term TODO. + */ + /* If excess == 0, no tree ops */ + __mem_cgroup_insert_exceeded(mz->memcg, mz, mctz, excess); + spin_unlock(&mctz->lock); + css_put(&mz->memcg->css); + loop++; + /* + * Could not reclaim anything and there are no more + * mem cgroups to try or we seem to be looping without + * reclaiming anything. + */ + if (!nr_reclaimed && + (next_mz == NULL || + loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS)) + break; + } while (!nr_reclaimed); + if (next_mz) + css_put(&next_mz->memcg->css); + return nr_reclaimed; +} + /** * mem_cgroup_force_empty_list - clears LRU of a group * @memcg: group to clear -- cgit v1.2.3-55-g7522