Messages in this thread Patch in this message | | | Date | Fri, 27 Mar 2009 14:01:47 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | [RFC][PATCH 1/8] soft limit support in res_counter |
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This is from Balbir's one. -Kame == From: Balbir Singh <balbir@linux.vnet.ibm.com> Changelog v2...v1 1. Add support for res_counter_check_soft_limit_locked. This is used by the hierarchy code.
Add an interface to allow get/set of soft limits. Soft limits for memory plus swap controller (memsw) is currently not supported. Resource counters have been enhanced to support soft limits and new type RES_SOFT_LIMIT has been added. Unlike hard limits, soft limits can be directly set and do not need any reclaim or checks before setting them to a newer value.
Kamezawa-San raised a question as to whether soft limit should belong to res_counter. Since all resources understand the basic concepts of hard and soft limits, it is justified to add soft limits here. Soft limits are a generic resource usage feature, even file system quotas support soft limits.
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> --- Index: mmotm-2.6.29-Mar23/include/linux/res_counter.h =================================================================== --- mmotm-2.6.29-Mar23.orig/include/linux/res_counter.h +++ mmotm-2.6.29-Mar23/include/linux/res_counter.h @@ -35,6 +35,10 @@ struct res_counter { */ unsigned long long limit; /* + * the limit that usage can be exceed + */ + unsigned long long soft_limit; + /* * the number of unsuccessful attempts to consume the resource */ unsigned long long failcnt; @@ -85,6 +89,7 @@ enum { RES_MAX_USAGE, RES_LIMIT, RES_FAILCNT, + RES_SOFT_LIMIT, }; /* @@ -130,6 +135,36 @@ static inline bool res_counter_limit_che return false; } +static inline bool res_counter_soft_limit_check_locked(struct res_counter *cnt) +{ + if (cnt->usage < cnt->soft_limit) + return true; + + return false; +} + +/** + * Get the difference between the usage and the soft limit + * @cnt: The counter + * + * Returns 0 if usage is less than or equal to soft limit + * The difference between usage and soft limit, otherwise. + */ +static inline unsigned long long +res_counter_soft_limit_excess(struct res_counter *cnt) +{ + unsigned long long excess; + unsigned long flags; + + spin_lock_irqsave(&cnt->lock, flags); + if (cnt->usage <= cnt->soft_limit) + excess = 0; + else + excess = cnt->usage - cnt->soft_limit; + spin_unlock_irqrestore(&cnt->lock, flags); + return excess; +} + /* * Helper function to detect if the cgroup is within it's limit or * not. It's currently called from cgroup_rss_prepare() @@ -145,6 +180,17 @@ static inline bool res_counter_check_und return ret; } +static inline bool res_counter_check_under_soft_limit(struct res_counter *cnt) +{ + bool ret; + unsigned long flags; + + spin_lock_irqsave(&cnt->lock, flags); + ret = res_counter_soft_limit_check_locked(cnt); + spin_unlock_irqrestore(&cnt->lock, flags); + return ret; +} + static inline void res_counter_reset_max(struct res_counter *cnt) { unsigned long flags; @@ -178,4 +224,16 @@ static inline int res_counter_set_limit( return ret; } +static inline int +res_counter_set_soft_limit(struct res_counter *cnt, + unsigned long long soft_limit) +{ + unsigned long flags; + + spin_lock_irqsave(&cnt->lock, flags); + cnt->soft_limit = soft_limit; + spin_unlock_irqrestore(&cnt->lock, flags); + return 0; +} + #endif Index: mmotm-2.6.29-Mar23/kernel/res_counter.c =================================================================== --- mmotm-2.6.29-Mar23.orig/kernel/res_counter.c +++ mmotm-2.6.29-Mar23/kernel/res_counter.c @@ -19,6 +19,7 @@ void res_counter_init(struct res_counter { spin_lock_init(&counter->lock); counter->limit = (unsigned long long)LLONG_MAX; + counter->soft_limit = (unsigned long long)LLONG_MAX; counter->parent = parent; } @@ -101,6 +102,8 @@ res_counter_member(struct res_counter *c return &counter->limit; case RES_FAILCNT: return &counter->failcnt; + case RES_SOFT_LIMIT: + return &counter->soft_limit; }; BUG(); Index: mmotm-2.6.29-Mar23/mm/memcontrol.c =================================================================== --- mmotm-2.6.29-Mar23.orig/mm/memcontrol.c +++ mmotm-2.6.29-Mar23/mm/memcontrol.c @@ -2002,6 +2002,20 @@ static int mem_cgroup_write(struct cgrou else ret = mem_cgroup_resize_memsw_limit(memcg, val); break; + case RES_SOFT_LIMIT: + ret = res_counter_memparse_write_strategy(buffer, &val); + if (ret) + break; + /* + * For memsw, soft limits are hard to implement in terms + * of semantics, for now, we support soft limits for + * control without swap + */ + if (type == _MEM) + ret = res_counter_set_soft_limit(&memcg->res, val); + else + ret = -EINVAL; + break; default: ret = -EINVAL; /* should be BUG() ? */ break; @@ -2251,6 +2265,12 @@ static struct cftype mem_cgroup_files[] .read_u64 = mem_cgroup_read, }, { + .name = "soft_limit_in_bytes", + .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT), + .write_string = mem_cgroup_write, + .read_u64 = mem_cgroup_read, + }, + { .name = "failcnt", .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT), .trigger = mem_cgroup_reset,
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