On Sun, Apr 24, 2011 at 7:21 PM, KOSAKI Motohiro
<kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
>> > > > > + sc.priority = priority;
>> > > > > + /* The swap token gets in the way of swapout... */
>> > > > > + if (!priority)
>> > > > > + disable_swap_token();
>> > > >
>> > > > Why?
>> > > >
>> > > > disable swap token mean "Please devest swap preventation privilege from
>> > > > owner task. Instead we endure swap storm and performance hit".
>> > > > However I doublt memcg memory shortage is good situation to make swap
>> > > > storm.
>> > > >
>> > >
>> > > I am not sure about that either way. we probably can leave as it is and
>> > make
>> > > corresponding change if real problem is observed?
>> >
>> > Why?
>> > This is not only memcg issue, but also can lead to global swap ping-pong.
>> >
>> > But I give up. I have no time to persuade you.
>> >
>> > Thank you for pointing that out. I didn't pay much attention on the
>> swap_token but just simply inherited
>> it from the global logic. Now after reading a bit more, i think you were
>> right about it. It would be a bad
>> idea to have memcg kswapds affecting much the global swap token being set.
>>
>> I will remove it from the next post.
>
> The better approach is swap-token recognize memcg and behave clever? :)
Ok, this makes sense for memcg case. Maybe I missed something on the
per-node balance_pgdat, where it seems it will blindly disable the
swap_token_mm if there is a one.
static inline int has_swap_token(struct mm_struct *mm)
{
>-------return (mm == swap_token_mm);
}
static inline void put_swap_token(struct mm_struct *mm)
{
>-------if (has_swap_token(mm))
>------->-------__put_swap_token(mm);
}
static inline void disable_swap_token(void)
{
>-------put_swap_token(swap_token_mm);
}
Should I include this patch into the per-memcg kswapd patset?
--Ying
>
>
>
> From 106c21d7f9cf8641592cbfe1416af66470af4f9a Mon Sep 17 00:00:00 2001
> From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> Date: Mon, 25 Apr 2011 10:57:54 +0900
> Subject: [PATCH] vmscan,memcg: memcg aware swap token
>
> Currently, memcg reclaim can disable swap token even if the swap token
> mm doesn't belong in its memory cgroup. It's slightly riskly. If an
> admin makes very small mem-cgroup and silly guy runs contenious heavy
> memory pressure workloa, whole tasks in the system are going to lose
> swap-token and then system may become unresponsive. That's bad.
>
> This patch adds 'memcg' parameter into disable_swap_token(). and if
> the parameter doesn't match swap-token, VM doesn't put swap-token.
>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> ---
> include/linux/memcontrol.h | 6 ++++++
> include/linux/swap.h | 24 +++++++++++++++++-------
> mm/memcontrol.c | 2 +-
> mm/thrash.c | 17 +++++++++++++++++
> mm/vmscan.c | 4 ++--
> 5 files changed, 43 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 6a0cffd..df572af 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -84,6 +84,7 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem);
>
> extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
> extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
> +extern struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm);
>
> static inline
> int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *cgroup)
> @@ -244,6 +245,11 @@ static inline struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
> return NULL;
> }
>
> +static inline struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
> +{
> + return NULL;
> +}
> +
> static inline int mm_match_cgroup(struct mm_struct *mm, struct mem_cgroup *mem)
> {
> return 1;
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 384eb5f..ccea15d 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -358,21 +358,31 @@ struct backing_dev_info;
> extern struct mm_struct *swap_token_mm;
> extern void grab_swap_token(struct mm_struct *);
> extern void __put_swap_token(struct mm_struct *);
> +extern int has_swap_token_memcg(struct mm_struct *mm, struct mem_cgroup *memcg);
>
> -static inline int has_swap_token(struct mm_struct *mm)
> +static inline
> +int has_swap_token(struct mm_struct *mm)
> {
> - return (mm == swap_token_mm);
> + return has_swap_token_memcg(mm, NULL);
> }
>
> -static inline void put_swap_token(struct mm_struct *mm)
> +static inline
> +void put_swap_token_memcg(struct mm_struct *mm, struct mem_cgroup *memcg)
> {
> - if (has_swap_token(mm))
> + if (has_swap_token_memcg(mm, memcg))
> __put_swap_token(mm);
> }
>
> -static inline void disable_swap_token(void)
> +static inline
> +void put_swap_token(struct mm_struct *mm)
> +{
> + return put_swap_token_memcg(mm, NULL);
> +}
> +
> +static inline
> +void disable_swap_token(struct mem_cgroup *memcg)
> {
> - put_swap_token(swap_token_mm);
> + put_swap_token_memcg(swap_token_mm, memcg);
> }
>
> #ifdef CONFIG_CGROUP_MEM_RES_CTLR
> @@ -500,7 +510,7 @@ static inline int has_swap_token(struct mm_struct *mm)
> return 0;
> }
>
> -static inline void disable_swap_token(void)
> +static inline void disable_swap_token(struct mem_cgroup *memcg)
> {
> }
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c2776f1..5683c7a 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -735,7 +735,7 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
> struct mem_cgroup, css);
> }
>
> -static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
> +struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
> {
> struct mem_cgroup *mem = NULL;
>
> diff --git a/mm/thrash.c b/mm/thrash.c
> index 2372d4e..f892a6e 100644
> --- a/mm/thrash.c
> +++ b/mm/thrash.c
> @@ -21,6 +21,7 @@
> #include <linux/mm.h>
> #include <linux/sched.h>
> #include <linux/swap.h>
> +#include <linux/memcontrol.h>
>
> static DEFINE_SPINLOCK(swap_token_lock);
> struct mm_struct *swap_token_mm;
> @@ -75,3 +76,19 @@ void __put_swap_token(struct mm_struct *mm)
> swap_token_mm = NULL;
> spin_unlock(&swap_token_lock);
> }
> +
> +int has_swap_token_memcg(struct mm_struct *mm, struct mem_cgroup *memcg)
> +{
> + if (memcg) {
> + struct mem_cgroup *swap_token_memcg;
> +
> + /*
> + * memcgroup reclaim can disable swap token only if token task
> + * is in the same cgroup.
> + */
> + swap_token_memcg = try_get_mem_cgroup_from_mm(swap_token_mm);
> + return ((mm == swap_token_mm) && (memcg == swap_token_memcg));
> + } else
> + return (mm == swap_token_mm);
> +}
> +
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b3a569f..19e179b 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2044,7 +2044,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
> for (priority = DEF_PRIORITY; priority >= 0; priority--) {
> sc->nr_scanned = 0;
> if (!priority)
> - disable_swap_token();
> + disable_swap_token(sc->mem_cgroup);
> shrink_zones(priority, zonelist, sc);
> /*
> * Don't shrink slabs when reclaiming memory from
> @@ -2353,7 +2353,7 @@ loop_again:
>
> /* The swap token gets in the way of swapout... */
> if (!priority)
> - disable_swap_token();
> + disable_swap_token(NULL);
>
> all_zones_ok = 1;
> balanced = 0;
> --
> 1.7.3.1
>
>
>
>
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