Re: [mm] [PATCH 2/4] Add the soft limit interface v2

Li Zefan
2008-02-19T07:35:38Z

Balbir Singh wrote:
> A new configuration file called soft_limit_in_bytes is added. The parsing
> and configuration rules remain the same as for the limit_in_bytes user
> interface.
>
> A global list of all memory cgroups over their soft limit is maintained.
> This list is then used to reclaim memory on global pressure. A cgroup is
> removed from the list when the cgroup is deleted.
>
> The global list is protected with a read-write spinlock.
>

You are not using read-write spinlock..

>
> Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
> ---
>
> mm/memcontrol.c | 33 ++++++++++++++++++++++++++++++++-
> 1 file changed, 32 insertions(+), 1 deletion(-)
>
> diff -puN mm/memcontrol.c~memory-controller-add-soft-limit-interface mm/memcontrol.c
> --- linux-2.6.25-rc2/mm/memcontrol.c~memory-controller-add-soft-limit-interface 2008-02-19 12:31:49.000000000 +0530
> +++ linux-2.6.25-rc2-balbir/mm/memcontrol.c 2008-02-19 12:31:49.000000000 +0530
> @@ -35,6 +35,10 @@
>
> struct cgroup_subsys mem_cgroup_subsys;
> static const int MEM_CGROUP_RECLAIM_RETRIES = 5;
> +static spinlock_t mem_cgroup_sl_list_lock; /* spin lock that protects */
> + /* the list of cgroups over*/
> + /* their soft limit */
> +static struct list_head mem_cgroup_sl_exceeded_list;
>
> /*
> * Statistics for memory cgroup.
> @@ -136,6 +140,10 @@ struct mem_cgroup {
> * statistics.
> */
> struct mem_cgroup_stat stat;
> + /*
> + * List of all mem_cgroup's that exceed their soft limit
> + */
> + struct list_head sl_exceeded_list;
> };
>
> /*
> @@ -679,6 +687,18 @@ retry:
> goto retry;
> }
>
> + /*
> + * If we exceed our soft limit, we get added to the list of
> + * cgroups over their soft limit
> + */
> + if (!res_counter_check_under_limit(&mem->res, RES_SOFT_LIMIT)) {
> + spin_lock_irqsave(&mem_cgroup_sl_list_lock, flags);
> + if (list_empty(&mem->sl_exceeded_list))
> + list_add_tail(&mem->sl_exceeded_list,
> + &mem_cgroup_sl_exceeded_list);
> + spin_unlock_irqrestore(&mem_cgroup_sl_list_lock, flags);
> + }
> +
> mz = page_cgroup_zoneinfo(pc);
> spin_lock_irqsave(&mz->lru_lock, flags);
> /* Update statistics vector */
> @@ -736,13 +756,14 @@ void mem_cgroup_uncharge(struct page_cgr
> if (atomic_dec_and_test(&pc->ref_cnt)) {
> page = pc->page;
> mz = page_cgroup_zoneinfo(pc);
> + mem = pc->mem_cgroup;
> /*
> * get page->cgroup and clear it under lock.
> * force_empty can drop page->cgroup without checking refcnt.
> */
> unlock_page_cgroup(page);
> +
> if (clear_page_cgroup(page, pc) == pc) {
> - mem = pc->mem_cgroup;
> css_put(&mem->css);
> res_counter_uncharge(&mem->res, PAGE_SIZE);
> spin_lock_irqsave(&mz->lru_lock, flags);
> @@ -1046,6 +1067,12 @@ static struct cftype mem_cgroup_files[]
> .name = "stat",
> .open = mem_control_stat_open,
> },
> + {
> + .name = "soft_limit_in_bytes",
> + .private = RES_SOFT_LIMIT,
> + .write = mem_cgroup_write,
> + .read = mem_cgroup_read,
> + },
> };
>
> static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
> @@ -1097,6 +1124,9 @@ mem_cgroup_create(struct cgroup_subsys *
> if (unlikely((cont->parent) == NULL)) {
> mem = &init_mem_cgroup;
> init_mm.mem_cgroup = mem;
> + INIT_LIST_HEAD(&mem->sl_exceeded_list);
> + spin_lock_init(&mem_cgroup_sl_list_lock);
> + INIT_LIST_HEAD(&mem_cgroup_sl_exceeded_list);
> } else
> mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL);
>
> @@ -1104,6 +1134,7 @@ mem_cgroup_create(struct cgroup_subsys *
> return NULL;
>
> res_counter_init(&mem->res);
> + INIT_LIST_HEAD(&mem->sl_exceeded_list);
>

mem->sl_exceeded_list initialized twice ?

> memset(&mem->info, 0, sizeof(mem->info));
>
> _
>