[Devel] Re: [PATCH 1/2] memcg: dirty pages accounting and limiting infrastructure
David Rientjes
rientjes at google.com
Sun Feb 21 13:28:35 PST 2010
On Sun, 21 Feb 2010, Andrea Righi wrote:
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 1f9b119..ba3fe0d 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -25,6 +25,16 @@ struct page_cgroup;
> struct page;
> struct mm_struct;
>
> +/* Cgroup memory statistics items exported to the kernel */
> +enum memcg_page_stat_item {
> + MEMCG_NR_FREE_PAGES,
> + MEMCG_NR_RECLAIMABLE_PAGES,
> + MEMCG_NR_FILE_DIRTY,
> + MEMCG_NR_WRITEBACK,
> + MEMCG_NR_WRITEBACK_TEMP,
> + MEMCG_NR_UNSTABLE_NFS,
> +};
> +
> #ifdef CONFIG_CGROUP_MEM_RES_CTLR
> /*
> * All "charge" functions with gfp_mask should use GFP_KERNEL or
> @@ -48,6 +58,8 @@ extern void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *ptr);
>
> extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
> gfp_t gfp_mask);
> +extern void mem_cgroup_charge_dirty(struct page *page,
> + enum zone_stat_item idx, int charge);
> extern void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru);
> extern void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru);
> extern void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru);
> @@ -117,6 +129,10 @@ extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
> extern int do_swap_account;
> #endif
>
> +extern unsigned long mem_cgroup_dirty_bytes(void);
> +
> +extern u64 mem_cgroup_page_state(enum memcg_page_stat_item item);
> +
> static inline bool mem_cgroup_disabled(void)
> {
> if (mem_cgroup_subsys.disabled)
> @@ -144,6 +160,11 @@ static inline int mem_cgroup_cache_charge(struct page *page,
> return 0;
> }
>
> +static inline void mem_cgroup_charge_dirty(struct page *page,
> + enum zone_stat_item idx, int charge)
> +{
> +}
> +
> static inline int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
> struct page *page, gfp_t gfp_mask, struct mem_cgroup **ptr)
> {
> @@ -312,6 +333,16 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
> return 0;
> }
>
> +static inline unsigned long mem_cgroup_dirty_bytes(void)
> +{
> + return vm_dirty_bytes;
> +}
> +
> +static inline u64 mem_cgroup_page_state(enum memcg_page_stat_item item)
> +{
> + return 0;
> +}
> +
> #endif /* CONFIG_CGROUP_MEM_CONT */
>
> #endif /* _LINUX_MEMCONTROL_H */
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 954032b..288b9a4 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -64,13 +64,18 @@ enum mem_cgroup_stat_index {
> /*
> * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
> */
> - MEM_CGROUP_STAT_CACHE, /* # of pages charged as cache */
> + MEM_CGROUP_STAT_CACHE, /* # of pages charged as cache */
> MEM_CGROUP_STAT_RSS, /* # of pages charged as anon rss */
> MEM_CGROUP_STAT_FILE_MAPPED, /* # of pages charged as file rss */
> MEM_CGROUP_STAT_PGPGIN_COUNT, /* # of pages paged in */
> MEM_CGROUP_STAT_PGPGOUT_COUNT, /* # of pages paged out */
> MEM_CGROUP_STAT_EVENTS, /* sum of pagein + pageout for internal use */
> MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
> + MEM_CGROUP_STAT_FILE_DIRTY, /* # of dirty pages in page cache */
> + MEM_CGROUP_STAT_WRITEBACK, /* # of pages under writeback */
> + MEM_CGROUP_STAT_WRITEBACK_TEMP, /* # of pages under writeback using
> + temporary buffers */
> + MEM_CGROUP_STAT_UNSTABLE_NFS, /* # of NFS unstable pages */
>
> MEM_CGROUP_STAT_NSTATS,
> };
> @@ -225,6 +230,9 @@ struct mem_cgroup {
> /* set when res.limit == memsw.limit */
> bool memsw_is_minimum;
>
> + /* control memory cgroup dirty pages */
> + unsigned long dirty_bytes;
> +
> /*
> * statistics. This must be placed at the end of memcg.
> */
> @@ -519,6 +527,67 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
> put_cpu();
> }
>
> +static struct mem_cgroup *get_mem_cgroup_from_page(struct page *page)
> +{
> + struct page_cgroup *pc;
> + struct mem_cgroup *mem = NULL;
> +
> + pc = lookup_page_cgroup(page);
> + if (unlikely(!pc))
> + return NULL;
> + lock_page_cgroup(pc);
> + if (PageCgroupUsed(pc)) {
> + mem = pc->mem_cgroup;
> + if (mem)
> + css_get(&mem->css);
> + }
> + unlock_page_cgroup(pc);
> + return mem;
> +}
Is it possible to merge this with try_get_mem_cgroup_from_page()?
> +
> +void mem_cgroup_charge_dirty(struct page *page,
> + enum zone_stat_item idx, int charge)
> +{
> + struct mem_cgroup *mem;
> + struct mem_cgroup_stat_cpu *cpustat;
> + unsigned long flags;
> + int cpu;
> +
> + if (mem_cgroup_disabled())
> + return;
> + /* Translate the zone_stat_item into a mem_cgroup_stat_index */
> + switch (idx) {
> + case NR_FILE_DIRTY:
> + idx = MEM_CGROUP_STAT_FILE_DIRTY;
> + break;
> + case NR_WRITEBACK:
> + idx = MEM_CGROUP_STAT_WRITEBACK;
> + break;
> + case NR_WRITEBACK_TEMP:
> + idx = MEM_CGROUP_STAT_WRITEBACK_TEMP;
> + break;
> + case NR_UNSTABLE_NFS:
> + idx = MEM_CGROUP_STAT_UNSTABLE_NFS;
> + break;
> + default:
> + return;
WARN()? We don't want to silently leak counters.
> + }
> + /* Charge the memory cgroup statistics */
> + mem = get_mem_cgroup_from_page(page);
> + if (!mem) {
> + mem = root_mem_cgroup;
> + css_get(&mem->css);
> + }
get_mem_cgroup_from_page() should probably handle the root_mem_cgroup case
and return a reference from it.
> +
> + local_irq_save(flags);
> + cpu = get_cpu();
> + cpustat = &mem->stat.cpustat[cpu];
> + __mem_cgroup_stat_add_safe(cpustat, idx, charge);
get_cpu()? Preemption is already disabled, just use smp_processor_id().
> + put_cpu();
> + local_irq_restore(flags);
> + css_put(&mem->css);
> +}
> +
> static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem,
> enum lru_list idx)
> {
> @@ -992,6 +1061,97 @@ static unsigned int get_swappiness(struct mem_cgroup *memcg)
> return swappiness;
> }
>
> +static unsigned long get_dirty_bytes(struct mem_cgroup *memcg)
> +{
> + struct cgroup *cgrp = memcg->css.cgroup;
> + unsigned long dirty_bytes;
> +
> + /* root ? */
> + if (cgrp->parent == NULL)
> + return vm_dirty_bytes;
> +
> + spin_lock(&memcg->reclaim_param_lock);
> + dirty_bytes = memcg->dirty_bytes;
> + spin_unlock(&memcg->reclaim_param_lock);
> +
> + return dirty_bytes;
> +}
> +
> +unsigned long mem_cgroup_dirty_bytes(void)
> +{
> + struct mem_cgroup *memcg;
> + unsigned long dirty_bytes;
> +
> + if (mem_cgroup_disabled())
> + return vm_dirty_bytes;
> +
> + rcu_read_lock();
> + memcg = mem_cgroup_from_task(current);
> + if (memcg == NULL)
> + dirty_bytes = vm_dirty_bytes;
> + else
> + dirty_bytes = get_dirty_bytes(memcg);
> + rcu_read_unlock();
The rcu_read_lock() isn't protecting anything here.
> +
> + return dirty_bytes;
> +}
> +
> +u64 mem_cgroup_page_state(enum memcg_page_stat_item item)
> +{
> + struct mem_cgroup *memcg;
> + struct cgroup *cgrp;
> + u64 ret = 0;
> +
> + if (mem_cgroup_disabled())
> + return 0;
> +
> + rcu_read_lock();
Again, this isn't necessary.
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