diff options
| -rw-r--r-- | Documentation/cgroups/memory.txt | 17 | ||||
| -rw-r--r-- | mm/memcontrol.c | 19 |
2 files changed, 30 insertions, 6 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index 1a608877b14e..af48135bd9b8 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -152,14 +152,19 @@ When swap is accounted, following files are added. usage of mem+swap is limited by memsw.limit_in_bytes. -Note: why 'mem+swap' rather than swap. +* why 'mem+swap' rather than swap. The global LRU(kswapd) can swap out arbitrary pages. Swap-out means to move account from memory to swap...there is no change in usage of -mem+swap. - -In other words, when we want to limit the usage of swap without affecting -global LRU, mem+swap limit is better than just limiting swap from OS point -of view. +mem+swap. In other words, when we want to limit the usage of swap without +affecting global LRU, mem+swap limit is better than just limiting swap from +OS point of view. + +* What happens when a cgroup hits memory.memsw.limit_in_bytes +When a cgroup his memory.memsw.limit_in_bytes, it's useless to do swap-out +in this cgroup. Then, swap-out will not be done by cgroup routine and file +caches are dropped. But as mentioned above, global LRU can do swapout memory +from it for sanity of the system's memory management state. You can't forbid +it by cgroup. 2.5 Reclaim diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a83e0395444b..6ceb6f2dbac2 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -177,6 +177,9 @@ struct mem_cgroup { unsigned int swappiness; + /* set when res.limit == memsw.limit */ + bool memsw_is_minimum; + /* * statistics. This must be placed at the end of memcg. */ @@ -847,6 +850,10 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem, int ret, total = 0; int loop = 0; + /* If memsw_is_minimum==1, swap-out is of-no-use. */ + if (root_mem->memsw_is_minimum) + noswap = true; + while (loop < 2) { victim = mem_cgroup_select_victim(root_mem); if (victim == root_mem) @@ -1752,6 +1759,12 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, break; } ret = res_counter_set_limit(&memcg->res, val); + if (!ret) { + if (memswlimit == val) + memcg->memsw_is_minimum = true; + else + memcg->memsw_is_minimum = false; + } mutex_unlock(&set_limit_mutex); if (!ret) @@ -1799,6 +1812,12 @@ static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg, break; } ret = res_counter_set_limit(&memcg->memsw, val); + if (!ret) { + if (memlimit == val) + memcg->memsw_is_minimum = true; + else + memcg->memsw_is_minimum = false; + } mutex_unlock(&set_limit_mutex); if (!ret) |