On Tue 28-06-11 17:39:58, KAMEZAWA Hiroyuki wrote:
> From b52bcd09843e903e5f184d0ee499909d072f3c8d Mon Sep 17 00:00:00 2001
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Date: Tue, 28 Jun 2011 15:45:38 +0900
> Subject: [PATCH 1/3] memcg: fix reclaimable lru check in memcg.
>
> Now, in mem_cgroup_hierarchical_reclaim(), mem_cgroup_local_usage()
> is used for checking whether the memcg contains reclaimable pages
> or not. If no pages in it, the routine skips it.
>
> But, mem_cgroup_local_usage() contains Unevictable pages and cannot
> handle "noswap" condition correctly. This doesn't work on a swapless
> system.
>
> This patch adds test_mem_cgroup_reclaimable() and replaces
> mem_cgroup_local_usage(). test_mem_cgroup_reclaimable() see LRU
> counter and returns correct answer to the caller.
> And this new function has "noswap" argument and can see only
> FILE LRU if necessary.
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
except for !CONFIG_NUMA issue - see bellow.
> @@ -1559,6 +1550,27 @@ mem_cgroup_select_victim(struct mem_cgroup *root_mem)
> return ret;
> }
>
> +/** test_mem_cgroup_node_reclaimable
> + * @mem: the target memcg
> + * @nid: the node ID to be checked.
> + * @noswap : specify true here if the user wants flle only information.
> + *
> + * This function returns whether the specified memcg contains any
> + * reclaimable pages on a node. Returns true if there are any reclaimable
> + * pages in the node.
> + */
> +static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *mem,
> + int nid, bool noswap)
> +{
> + if (mem_cgroup_node_nr_file_lru_pages(mem, nid))
> + return true;
I do not see definition of mem_cgroup_node_nr_file_lru_pages for
!MAX_NUMNODES==1 (resp. !CONFIG_NUMA) and you are calling this function
also from that context.
> #if MAX_NUMNODES > 1
>
> /*
> @@ -1580,15 +1592,8 @@ static void mem_cgroup_may_update_nodemask(struct mem_cgroup *mem)
>
> for_each_node_mask(nid, node_states[N_HIGH_MEMORY]) {
>
> - if (mem_cgroup_get_zonestat_node(mem, nid, LRU_INACTIVE_FILE) ||
> - mem_cgroup_get_zonestat_node(mem, nid, LRU_ACTIVE_FILE))
> - continue;
> -
> - if (total_swap_pages &&
> - (mem_cgroup_get_zonestat_node(mem, nid, LRU_INACTIVE_ANON) ||
> - mem_cgroup_get_zonestat_node(mem, nid, LRU_ACTIVE_ANON)))
> - continue;
> - node_clear(nid, mem->scan_nodes);
> + if (!test_mem_cgroup_node_reclaimable(mem, nid, false))
> + node_clear(nid, mem->scan_nodes);
Nice clean up.
> @@ -1627,11 +1632,51 @@ int mem_cgroup_select_victim_node(struct mem_cgroup *mem)
> return node;
> }
>
> +/*
> + * Check all nodes whether it contains reclaimable pages or not.
> + * For quick scan, we make use of scan_nodes. This will allow us to skip
> + * unused nodes. But scan_nodes is lazily updated and may not cotain
> + * enough new information. We need to do double check.
> + */
> +bool mem_cgroup_reclaimable(struct mem_cgroup *mem, bool noswap)
> +{
> + int nid;
> +
> + /*
> + * quick check...making use of scan_node.
> + * We can skip unused nodes.
> + */
> + if (!nodes_empty(mem->scan_nodes)) {
> + for (nid = first_node(mem->scan_nodes);
> + nid < MAX_NUMNODES;
> + nid = next_node(nid, mem->scan_nodes)) {
> +
> + if (test_mem_cgroup_node_reclaimable(mem, nid, noswap))
> + return true;
> + }
> + }
> + /*
> + * Check rest of nodes.
> + */
> + for_each_node_state(nid, N_HIGH_MEMORY) {
> + if (node_isset(nid, mem->scan_nodes))
> + continue;
> + if (test_mem_cgroup_node_reclaimable(mem, nid, noswap))
> + return true;
> + }
> + return false;
> +}
> +
> #else
This is #else if MAX_NUMNODES == 1 AFAICS
> int mem_cgroup_select_victim_node(struct mem_cgroup *mem)
> {
> return 0;
> }
> +
> +bool mem_cgroup_reclaimable(struct mem_cgroup *mem, bool noswap)
> +{
> + return test_mem_cgroup_node_reclaimable(mem, 0, noswap);
> +}
> #endif
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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