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Date: Thu, 12 Mar 2009 09:24:44 +0530
From: Balbir Singh <balbir@...ux.vnet.ibm.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: "linux-mm@...ck.org" <linux-mm@...ck.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>,
"kosaki.motohiro@...fujitsu.com" <kosaki.motohiro@...fujitsu.com>
Subject: Re: [RFC][PATCH 2/5] add softlimit to res_counter
* KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> [2009-03-12 09:56:12]:
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>
> Adds an interface for defining sotlimit per memcg. (no handler in this patch.)
> softlimit paramater itself is added to res_counter and
> res_counter_set_softlimit() and
> res_counter_check_under_softlimit() is provided as an interface.
>
>
> Changelog v2->v3:
> - softlimit is moved to res_counter
Good, this is very similar to the patch I have in my post as well. Please feel
free to add my signed-off-by on this patch, but please see below for
comments.
> Changelog v1->v2:
> - For refactoring, divided a patch into 2 part and this patch just
> involves memory.softlimit interface.
> - Removed governor-detect routine, it was buggy in design.
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> ---
> include/linux/res_counter.h | 9 +++++++++
> kernel/res_counter.c | 29 +++++++++++++++++++++++++++++
> mm/memcontrol.c | 12 ++++++++++++
> 3 files changed, 50 insertions(+)
>
> Index: mmotm-2.6.29-Mar10/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.29-Mar10.orig/mm/memcontrol.c
> +++ mmotm-2.6.29-Mar10/mm/memcontrol.c
> @@ -2002,6 +2002,12 @@ static int mem_cgroup_write(struct cgrou
> else
> ret = mem_cgroup_resize_memsw_limit(memcg, val);
> break;
> + case RES_SOFTLIMIT:
> + ret = res_counter_memparse_write_strategy(buffer, &val);
> + if (ret)
> + break;
> + ret = res_counter_set_softlimit(&memcg->res, val);
> + break;
> default:
> ret = -EINVAL; /* should be BUG() ? */
> break;
> @@ -2251,6 +2257,12 @@ static struct cftype mem_cgroup_files[]
> .read_u64 = mem_cgroup_read,
> },
> {
> + .name = "softlimit_in_bytes",
> + .private = MEMFILE_PRIVATE(_MEM, RES_SOFTLIMIT),
> + .write_string = mem_cgroup_write,
> + .read_u64 = mem_cgroup_read,
> + },
> + {
> .name = "failcnt",
> .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
> .trigger = mem_cgroup_reset,
> Index: mmotm-2.6.29-Mar10/include/linux/res_counter.h
> ===================================================================
> --- mmotm-2.6.29-Mar10.orig/include/linux/res_counter.h
> +++ mmotm-2.6.29-Mar10/include/linux/res_counter.h
> @@ -39,6 +39,10 @@ struct res_counter {
> */
> unsigned long long failcnt;
> /*
> + * the softlimit.
> + */
> + unsigned long long softlimit;
> + /*
> * the lock to protect all of the above.
> * the routines below consider this to be IRQ-safe
> */
> @@ -85,6 +89,7 @@ enum {
> RES_MAX_USAGE,
> RES_LIMIT,
> RES_FAILCNT,
> + RES_SOFTLIMIT,
> };
>
> /*
> @@ -178,4 +183,8 @@ static inline int res_counter_set_limit(
> return ret;
> }
>
> +/* res_counter's softlimit check can handles hierarchy in proper way */
> +int res_counter_set_softlimit(struct res_counter *cnt, unsigned long long val);
> +bool res_counter_check_under_softlimit(struct res_counter *cnt);
> +
> #endif
> Index: mmotm-2.6.29-Mar10/kernel/res_counter.c
> ===================================================================
> --- mmotm-2.6.29-Mar10.orig/kernel/res_counter.c
> +++ mmotm-2.6.29-Mar10/kernel/res_counter.c
> @@ -20,6 +20,7 @@ void res_counter_init(struct res_counter
> spin_lock_init(&counter->lock);
> counter->limit = (unsigned long long)LLONG_MAX;
> counter->parent = parent;
> + counter->softlimit = (unsigned long long)LLONG_MAX;
> }
>
> int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
> @@ -88,6 +89,32 @@ void res_counter_uncharge(struct res_cou
> local_irq_restore(flags);
> }
>
> +int res_counter_set_softlimit(struct res_counter *cnt, unsigned long long val)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&cnt->lock, flags);
> + cnt->softlimit = val;
> + spin_unlock_irqrestore(&cnt->lock, flags);
> + return 0;
> +}
> +
> +bool res_counter_check_under_softlimit(struct res_counter *cnt)
> +{
> + struct res_counter *c;
> + unsigned long flags;
> + bool ret = true;
> +
> + local_irq_save(flags);
> + for (c = cnt; ret && c != NULL; c = c->parent) {
> + spin_lock(&c->lock);
> + if (c->softlimit < c->usage)
> + ret = false;
So if a child was under the soft limit and the parent is *not*, we
_override_ ret and return false?
> + spin_unlock(&c->lock);
> + }
> + local_irq_restore(flags);
> + return ret;
> +}
Why is the check_under_softlimit hierarchical? BTW, this patch is
buggy. See above.
>
> static inline unsigned long long *
> res_counter_member(struct res_counter *counter, int member)
> @@ -101,6 +128,8 @@ res_counter_member(struct res_counter *c
> return &counter->limit;
> case RES_FAILCNT:
> return &counter->failcnt;
> + case RES_SOFTLIMIT:
> + return &counter->softlimit;
> };
>
> BUG();
>
>
--
Balbir
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