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Message-Id: <20080613183402.4f31eb96.kamezawa.hiroyu@jp.fujitsu.com>
Date: Fri, 13 Jun 2008 18:34:02 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: "linux-mm@...ck.org" <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>,
"menage@...gle.com" <menage@...gle.com>,
"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>,
"xemul@...nvz.org" <xemul@...nvz.org>,
"yamamoto@...inux.co.jp" <yamamoto@...inux.co.jp>,
"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>,
"lizf@...fujitsu.com" <lizf@...fujitsu.com>
Subject: [PATCH 4/6] res_counter: basic hierarchy support
Add a hierarhy support to res_counter. This patch itself just supports
"No Hierarchy" hierarchy, as a default/basic hierarchy system.
Changelog: v3 -> v4.
- cut out from hardwall hierarchy patch set.
- just support "No hierarchy" model.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
---
Documentation/controllers/resource_counter.txt | 27 +++++-
include/linux/res_counter.h | 15 +++
kernel/res_counter.c | 107 ++++++++++++++++++++-----
mm/memcontrol.c | 1
4 files changed, 129 insertions(+), 21 deletions(-)
Index: linux-2.6.26-rc5-mm3/include/linux/res_counter.h
===================================================================
--- linux-2.6.26-rc5-mm3.orig/include/linux/res_counter.h
+++ linux-2.6.26-rc5-mm3/include/linux/res_counter.h
@@ -21,8 +21,13 @@
* the helpers described beyond
*/
+enum res_cont_hierarchy_model {
+ RES_CONT_NO_HIERARCHY,
+};
+
struct res_counter;
struct res_counter_ops {
+ enum res_cont_hierarchy_model hierarchy_model;
/* called when the subsystem has to reduce the usage. */
int (*shrink_usage)(struct res_counter *cnt, unsigned long long val,
int retry_count);
@@ -46,6 +51,10 @@ struct res_counter {
*/
unsigned long long failcnt;
/*
+ * parent of this counter in hierarchy. if root, this is NULL.
+ */
+ struct res_counter *parent;
+ /*
* registered callbacks etc...for res_counter.
*/
struct res_counter_ops ops;
@@ -101,6 +110,12 @@ static inline void res_counter_init(stru
res_counter_init_ops(counter, NULL);
}
+void res_counter_init_hierarchy(struct res_counter *counter,
+ struct res_counter *parent);
+
+int res_counter_set_ops(struct res_counter *counter,
+ struct res_counter_ops *ops);
+
/*
* charge - try to consume more resource.
*
Index: linux-2.6.26-rc5-mm3/kernel/res_counter.c
===================================================================
--- linux-2.6.26-rc5-mm3.orig/kernel/res_counter.c
+++ linux-2.6.26-rc5-mm3/kernel/res_counter.c
@@ -30,8 +30,70 @@ void res_counter_init_ops(struct res_cou
counter->limit = (unsigned long long)LLONG_MAX;
if (ops)
counter->ops = *ops;
+ counter->parent = NULL;
+}
+
+void __res_counter_init_hierarchy_core(struct res_counter *counter)
+{
+ switch (counter->ops.hierarchy_model) {
+ case RES_CONT_NO_HIERARCHY:
+ counter->limit = (unsigned long long)LLONG_MAX;
+ break;
+ default:
+ break;
+ }
+ return;
+}
+
+
+/**
+ * res_counter_init_hierarchy() -- initialize res_counter under some hierarchy.
+ * @counter: a counter will be initialized.
+ * @parent: parent of counter.
+ *
+ * parent->ops is copied to counter->ops and counter will be initialized
+ * to be suitable style for the hierarchy model.
+ */
+void res_counter_init_hierarchy(struct res_counter *counter,
+ struct res_counter *parent)
+{
+ struct res_counter_ops *ops = NULL;
+
+ if (parent)
+ ops = &parent->ops;
+ res_counter_init_ops(counter, ops);
+ counter->parent = parent;
+
+ __res_counter_init_hierarchy_core(counter);
}
+/**
+ * res_counter_set_ops() -- reset res->counter.ops to be passed ops.
+ * @coutner: a counter to be set ops.
+ * @ops: res_counter_ops
+ *
+ * This operations is allowed only when there is no parent or parent's
+ * hierarchy_model == RES_CONT_NO_HIERARCHY. returns 0 at success.
+ */
+
+int res_counter_set_ops(struct res_counter *counter,
+ struct res_counter_ops *ops)
+{
+ struct res_counter *parent;
+ /*
+ * This operation is allowed only when parents's hierarchy
+ * is NO_HIERARCHY or this is ROOT.
+ */
+ parent = counter->parent;
+ if (parent && parent->ops.hierarchy_model != RES_CONT_NO_HIERARCHY)
+ return -EINVAL;
+
+ counter->ops = *ops;
+
+ return 0;
+}
+
+
int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
{
if (counter->usage + val > counter->limit) {
@@ -125,30 +187,39 @@ static int res_counter_resize_limit(stru
int retry_count = 0;
int ret = -EBUSY;
unsigned long flags;
+ enum model = RES_CONT_NO_HIERARCHY;
BUG_ON(!cnt->ops.shrink_usage);
- while (1) {
- spin_lock_irqsave(&cnt->lock, flags);
- if (cnt->usage <= val) {
- cnt->limit = val;
- ret = 0;
- spin_unlock_irqrestore(&cnt->lock, flags);
- break;
- }
- BUG_ON(val > cnt->limit);
- spin_unlock_irqrestore(&cnt->lock, flags);
+ switch (model) {
+ case RES_CONT_NO_HIERARCHY:
/*
- * Rest before calling callback().... rest after callback
- * tends to add difference between the result of callback and
- * the check in next loop.
+ * shrink usage to be below the new limit.
*/
- cond_resched();
+ while (1) {
+ spin_lock_irqsave(&cnt->lock, flags);
+ if (cnt->usage <= val) {
+ cnt->limit = val;
+ ret = 0;
+ }
+ spin_unlock_irqrestore(&cnt->lock, flags);
+ if (!ret)
+ break;
+ /*
+ * Rest before calling callback().... rest after
+ * callback tends to add difference between the result
+ * of callback and the check in next loop.
+ */
+ cond_resched();
- ret = cnt->ops.shrink_usage(cnt, val, retry_count);
- if (!ret)
- break;
- retry_count++;
+ ret = cnt->ops.shrink_usage(cnt, val, retry_count);
+ if (!ret)
+ break;
+ retry_count++;
+ }
+ break;
+ default:
+ BUG();
}
return ret;
}
Index: linux-2.6.26-rc5-mm3/Documentation/controllers/resource_counter.txt
===================================================================
--- linux-2.6.26-rc5-mm3.orig/Documentation/controllers/resource_counter.txt
+++ linux-2.6.26-rc5-mm3/Documentation/controllers/resource_counter.txt
@@ -39,11 +39,14 @@ to work with it.
The failcnt stands for "failures counter". This is the number of
resource allocation attempts that failed.
- e. res_counter_ops.
+ e. parent
+ parent of this res_counter under hierarchy.
+
+ f. res_counter_ops.
Callbacks for helping resource_counter per each subsystem.
- shrink_usage() .... called at limit change (decrease).
- f. spinlock_t lock
+ g. spinlock_t lock
Protects changes of the above values.
@@ -157,7 +160,25 @@ counter fields. They are recommended to
Returns 0 at success. Any error code is acceptable but -EBUSY will be
suitable to show "the kernel can't shrink usage."
-6. Usage example
+6. Hierarchy
+
+ Groups of res_counter can be controlled under some tree (cgroup tree).
+ Taking the tree into account, res_counter can be under some hierarchical
+ control. THe res_counter itself supports hierarchy_model and calls
+ registered callbacks at suitable events.
+
+ For keeping sanity of hierarchy, hierarchy_model of a res_counter can be
+ changed when parent's hierarchy_model is RES_CONT_NO_HIERARCHY.
+ res_counter doesn't count # of children by itself but some subysystem should
+ be aware that it has no children if necessary.
+ (don't want to fully duplicate cgroup's hierarchy. Cost of remembering parent
+ is cheap.)
+
+ a. Independent hierarchy (RES_CONT_NO_HIERARCHY) model
+ This is no relationship between parent and children.
+
+
+7. Usage example
a. Declare a task group (take a look at cgroups subsystem for this) and
fold a res_counter into it
Index: linux-2.6.26-rc5-mm3/mm/memcontrol.c
===================================================================
--- linux-2.6.26-rc5-mm3.orig/mm/memcontrol.c
+++ linux-2.6.26-rc5-mm3/mm/memcontrol.c
@@ -1086,6 +1086,7 @@ static void mem_cgroup_free(struct mem_c
}
struct res_counter_ops root_ops = {
+ .hierarchy_model = RES_CONT_NO_HIERARCHY,
.shrink_usage = mem_cgroup_shrink_usage_to,
};
--
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