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Message-Id: <20100222092242.98df82e4.kamezawa.hiroyu@jp.fujitsu.com>
Date: Mon, 22 Feb 2010 09:22:42 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: Andrea Righi <arighi@...eler.com>
Cc: Balbir Singh <balbir@...ux.vnet.ibm.com>,
Suleiman Souhlal <suleiman@...gle.com>,
Vivek Goyal <vgoyal@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
containers@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] memcg: dirty pages accounting and limiting
infrastructure
On Sun, 21 Feb 2010 16:18:44 +0100
Andrea Righi <arighi@...eler.com> wrote:
> Infrastructure to account dirty pages per cgroup + add memory.dirty_bytes limit
> in cgroupfs.
>
> Signed-off-by: Andrea Righi <arighi@...eler.com>
Looks clean in general. But some confliction with memcg in mmotm.
And please CC: to linux-mm@...ck.org when you modify memcg.
> ---
> include/linux/memcontrol.h | 31 ++++++
> mm/memcontrol.c | 218 +++++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 248 insertions(+), 1 deletions(-)
>
> 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;
> +}
> +
Hmm. do we need to get refcnt for dirty page accounting ?
> +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;
> + }
> + /* Charge the memory cgroup statistics */
> + mem = get_mem_cgroup_from_page(page);
> + if (!mem) {
> + mem = root_mem_cgroup;
> + css_get(&mem->css);
> + }
> +
> + local_irq_save(flags);
> + cpu = get_cpu();
> + cpustat = &mem->stat.cpustat[cpu];
> + __mem_cgroup_stat_add_safe(cpustat, idx, charge);
> + put_cpu();
> + local_irq_restore(flags);
> + css_put(&mem->css);
> +}
This patch will conflict with mmotm. per_cpu stats are all rewritten.
In 1st impression, I think you should add DIRTY/WRITEBACK/UNSTABLE flag to
page_cgroup. If not, you can never handle migration.
And css_get()/css_put() is very heavy operation. (You can see it by perf, I think.)
So,
pc = lookup_page_cgroup(page);
lock_page_cgroup(pc);
mem = pc->page_cgroup;
if (mem && PageCgroupUsed(pc)) {
/* account */
}
unlock_page_cgroup(pc);
is better, rather than adding accessing function.
memcg is stable when USED page_cgroup is under lock.
> +
> 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;
We have mem_cgroup_is_root() macro.
> +
> + spin_lock(&memcg->reclaim_param_lock);
> + dirty_bytes = memcg->dirty_bytes;
> + spin_unlock(&memcg->reclaim_param_lock);
> +
> + return dirty_bytes;
> +}
Hmm...do we need spinlock ? You use "unsigned long", then, read-write
is always atomic if not read-modify-write.
> +
> +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();
> +
> + 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();
> + memcg = mem_cgroup_from_task(current);
> + if (memcg == NULL)
> + goto out;
> + cgrp = memcg->css.cgroup;
> + /* Use system-wide statistics for the root cgroup */
> + if (cgrp->parent == NULL)
> + goto out;
mem_cgroup_is_root() again.
> + switch (item) {
> + case MEMCG_NR_FREE_PAGES:
> + ret = res_counter_read_u64(&memcg->res, RES_LIMIT) -
> + res_counter_read_u64(&memcg->res, RES_USAGE);
> + /*
> + * Translate free memory in pages and ensure we never return 0.
> + */
> + ret = (ret >> PAGE_SHIFT) + 1;
> + break;
> + case MEMCG_NR_RECLAIMABLE_PAGES:
> + ret = mem_cgroup_read_stat(&memcg->stat, LRU_ACTIVE_ANON) +
> + mem_cgroup_read_stat(&memcg->stat, LRU_ACTIVE_FILE) +
> + mem_cgroup_read_stat(&memcg->stat, LRU_INACTIVE_ANON) +
> + mem_cgroup_read_stat(&memcg->stat, LRU_INACTIVE_FILE);
> + break;
> + case MEMCG_NR_FILE_DIRTY:
> + ret = mem_cgroup_read_stat(&memcg->stat,
> + MEM_CGROUP_STAT_FILE_DIRTY);
> + break;
> + case MEMCG_NR_WRITEBACK:
> + ret = mem_cgroup_read_stat(&memcg->stat,
> + MEM_CGROUP_STAT_WRITEBACK);
> + break;
> + case MEMCG_NR_WRITEBACK_TEMP:
> + ret = mem_cgroup_read_stat(&memcg->stat,
> + MEM_CGROUP_STAT_WRITEBACK_TEMP);
> + break;
> + case MEMCG_NR_UNSTABLE_NFS:
> + ret = mem_cgroup_read_stat(&memcg->stat,
> + MEM_CGROUP_STAT_UNSTABLE_NFS);
> + break;
> + default:
> + WARN_ON(1);
> + }
> +out:
> + rcu_read_unlock();
Hmm. A concern here is that whether you have to consider
"hierarchical accounting" or not. It's design descision but you have
to describe "dirty limit doesn't handle hierarchical accounting"
somewhere. But I should read 2nd patch before I comment more.
nitpick: When I add "per-memcg, not for hierarchy" function, I tend to
add _local_ in the function name. As mem_cgroup_get_local_stat().
> + return ret;
> +}
> +
> static int mem_cgroup_count_children_cb(struct mem_cgroup *mem, void *data)
> {
> int *val = data;
> @@ -2874,6 +3034,10 @@ enum {
> MCS_PGPGIN,
> MCS_PGPGOUT,
> MCS_SWAP,
> + MCS_FILE_DIRTY,
> + MCS_WRITEBACK,
> + MCS_WRITEBACK_TEMP,
> + MCS_UNSTABLE_NFS,
> MCS_INACTIVE_ANON,
> MCS_ACTIVE_ANON,
> MCS_INACTIVE_FILE,
> @@ -2896,6 +3060,10 @@ struct {
> {"pgpgin", "total_pgpgin"},
> {"pgpgout", "total_pgpgout"},
> {"swap", "total_swap"},
> + {"filedirty", "dirty_pages"},
> + {"writeback", "writeback_pages"},
> + {"writeback_tmp", "writeback_temp_pages"},
> + {"nfs", "nfs_unstable"},
> {"inactive_anon", "total_inactive_anon"},
> {"active_anon", "total_active_anon"},
> {"inactive_file", "total_inactive_file"},
> @@ -2924,6 +3092,14 @@ static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data)
> val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_SWAPOUT);
> s->stat[MCS_SWAP] += val * PAGE_SIZE;
> }
> + val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_FILE_DIRTY);
> + s->stat[MCS_FILE_DIRTY] += val;
> + val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_WRITEBACK);
> + s->stat[MCS_WRITEBACK] += val;
> + val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_WRITEBACK_TEMP);
> + s->stat[MCS_WRITEBACK_TEMP] += val;
> + val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_UNSTABLE_NFS);
> + s->stat[MCS_UNSTABLE_NFS] += val;
>
> /* per zone stat */
> val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_ANON);
> @@ -3049,6 +3225,41 @@ static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
> return 0;
> }
>
> +static u64 mem_cgroup_dirty_bytes_read(struct cgroup *cgrp, struct cftype *cft)
> +{
> + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> +
> + return get_dirty_bytes(memcg);
> +}
> +
> +static int mem_cgroup_dirty_bytes_write(struct cgroup *cgrp, struct cftype *cft,
> + u64 val)
> +{
> + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> + struct mem_cgroup *parent;
> +
> + if (cgrp->parent == NULL)
> + return -EINVAL;
> +
> + parent = mem_cgroup_from_cont(cgrp->parent);
> +
> + cgroup_lock();
> +
> + /* If under hierarchy, only empty-root can set this value */
> + if ((parent->use_hierarchy) ||
> + (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
> + cgroup_unlock();
> + return -EINVAL;
> + }
Okay, then, only hierarchy root can set the value.
Please descirbe this kind of important things in patch description.
Thanks.
-Kame
> +
> + spin_lock(&memcg->reclaim_param_lock);
> + memcg->dirty_bytes = val;
> + spin_unlock(&memcg->reclaim_param_lock);
> +
> + cgroup_unlock();
> +
> + return 0;
> +}
>
> static struct cftype mem_cgroup_files[] = {
> {
> @@ -3098,6 +3309,11 @@ static struct cftype mem_cgroup_files[] = {
> .read_u64 = mem_cgroup_swappiness_read,
> .write_u64 = mem_cgroup_swappiness_write,
> },
> + {
> + .name = "dirty_bytes",
> + .read_u64 = mem_cgroup_dirty_bytes_read,
> + .write_u64 = mem_cgroup_dirty_bytes_write,
> + },
> };
>
> #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> --
> 1.6.3.3
>
>
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