Messages in this thread | | | Date | Mon, 2 Mar 2009 11:03:23 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH 2/4] Memory controller soft limit interface (v3) |
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On Sun, 01 Mar 2009 12:00:11 +0530 Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> > 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. > I don't convice adding more logics to res_counter is a good to do, yet.
Thanks, -Kame
> Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> > --- > > include/linux/res_counter.h | 47 +++++++++++++++++++++++++++++++++++++++++++ > kernel/res_counter.c | 3 +++ > mm/memcontrol.c | 20 ++++++++++++++++++ > 3 files changed, 70 insertions(+), 0 deletions(-) > > > diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h > index 4c5bcf6..b5f14fa 100644 > --- a/include/linux/res_counter.h > +++ b/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_check_locked(struct res_counter *cnt) > 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() > @@ -178,4 +213,16 @@ static inline int res_counter_set_limit(struct res_counter *cnt, > 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 > diff --git a/kernel/res_counter.c b/kernel/res_counter.c > index bf8e753..4e6dafe 100644 > --- a/kernel/res_counter.c > +++ b/kernel/res_counter.c > @@ -19,6 +19,7 @@ void res_counter_init(struct res_counter *counter, struct res_counter *parent) > { > 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 *counter, int member) > return &counter->limit; > case RES_FAILCNT: > return &counter->failcnt; > + case RES_SOFT_LIMIT: > + return &counter->soft_limit; > }; > > BUG(); > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 7bb14fd..75a7b1a 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1939,6 +1939,20 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft, > 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; > @@ -2188,6 +2202,12 @@ 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, > > -- > Balbir > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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