[PATCH 04/12] Add task logic to resource groups

Chandra Seetharaman
2006-04-28T01:34:58Z

04/12 - tasksupport

Adds logic to support adding/removing task to/from a resource group
Provides interface to set a task's resource group.
--

Signed-Off-By: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-Off-By: Matt Helsley <matthltc@us.ibm.com>

include/linux/sched.h | 4 +
kernel/res_group/Makefile | 2
kernel/res_group/local.h | 1
kernel/res_group/res_group.c | 25 +++++++
kernel/res_group/task.c | 145 +++++++++++++++++++++++++++++++++++++++++++
5 files changed, 176 insertions(+), 1 deletion(-)

Index: linux-2617-rc3/include/linux/sched.h
===================================================================
--- linux-2617-rc3.orig/include/linux/sched.h 2006-04-27 09:22:14.000000000 -0700
+++ linux-2617-rc3/include/linux/sched.h 2006-04-27 09:22:16.000000000 -0700
@@ -888,6 +888,10 @@ struct task_struct {
* cache last used pipe for splice
*/
struct pipe_inode_info *splice_pipe;
+#ifdef CONFIG_RES_GROUPS
+ struct resource_group *res_group;
+ struct list_head member_list; /* list of tasks in the resource group */
+#endif /* CONFIG_RES_GROUPS */
};

static inline pid_t process_group(struct task_struct *tsk)
Index: linux-2617-rc3/kernel/res_group/task.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2617-rc3/kernel/res_group/task.c 2006-04-27 09:22:16.000000000 -0700
@@ -0,0 +1,145 @@
+/* task.c - Resource Groups
+ *
+ * Copyright (C) Hubertus Franke, IBM Corp. 2003,2004
+ * (C) Shailabh Nagar, IBM Corp. 2003
+ * (C) Chandra Seetharaman, IBM Corp. 2003, 2004, 2005
+ * (C) Vivek Kashyap, IBM Corp. 2004
+ *
+ * Latest version, more details at http://ckrm.sf.net
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+#include <linux/sched.h>
+#include <linux/module.h>
+#include "local.h"
+
+static inline struct resource_group
+ *remove_from_old_rgroup(struct task_struct *tsk)
+{
+ struct resource_group *rgroup;
+
+retry:
+ rgroup = tsk->res_group;
+ if (rgroup == NO_RES_GROUP)
+ goto done;
+
+ spin_lock(&rgroup->group_lock);
+ if (rgroup != tsk->res_group) { /* lost the race, retry */
+ spin_unlock(&rgroup->group_lock);
+ goto retry;
+ }
+ /* take out of old resource group */
+ list_del_init(&tsk->member_list);
+ tsk->res_group = NO_RES_GROUP;
+ spin_unlock(&rgroup->group_lock);
+done:
+ return rgroup;
+}
+
+static void move_to_new_rgroup(struct task_struct *tsk,
+ struct resource_group *new_rgroup)
+{
+ BUG_ON(!list_empty(&tsk->member_list));
+ BUG_ON(tsk->res_group != NO_RES_GROUP);
+
+ spin_lock(&new_rgroup->group_lock);
+ tsk->res_group = new_rgroup;
+ list_add(&tsk->member_list, &new_rgroup->task_list);
+ spin_unlock(&new_rgroup->group_lock);
+}
+
+static void notify_res_ctlrs(struct task_struct *tsk,
+ struct resource_group *old_rgroup, struct resource_group *new_rgroup)
+{
+ int i;
+ struct res_controller *ctlr;
+ struct res_shares *old_shares, *new_shares;
+
+ for (i = 0; i < MAX_RES_CTLRS; i++) {
+ ctlr = get_controller_by_id(i);
+ if (ctlr == NULL)
+ continue;
+ if (ctlr->move_task) {
+ old_shares = get_controller_shares(old_rgroup, ctlr);
+ new_shares = get_controller_shares(new_rgroup, ctlr);
+ ctlr->move_task(tsk, old_shares, new_shares);
+ }
+ put_controller(ctlr);
+ }
+}
+
+/*
+ * Change the resource group of the given task to "new_rgroup"
+ *
+ * Caller is responsible to make sure the task structure stays put
+ * through this function.
+ *
+ * This function should be called without holding group_lock of
+ * new_rgroup and tsk->res_group.
+ *
+ * Called with a reference to the new resource group held. The reference is
+ * dropped only when the task is assigned to a different resource group
+ * or when the task exits.
+ */
+static void __set_res_group(struct task_struct *tsk,
+ struct resource_group *new_rgroup)
+{
+ struct resource_group *old_rgroup;
+
+retry:
+ old_rgroup = remove_from_old_rgroup(tsk);
+
+ /* task is exiting or is moving to a different resource group. */
+ if (old_rgroup == NO_RES_GROUP) {
+ /* In the exit path, must succeed */
+ if (new_rgroup == NO_RES_GROUP)
+ goto retry;
+ kref_put(&new_rgroup->ref, release_res_group);
+ return;
+ }
+
+ /*
+ * notify resource controllers before we actually set the resource
+ * group in the task to avoid a race with notify_res_ctlrs being
+ * called from another __set_res_group.
+ */
+ notify_res_ctlrs(tsk, old_rgroup, new_rgroup);
+ if (new_rgroup != NO_RES_GROUP)
+ move_to_new_rgroup(tsk, new_rgroup);
+ kref_put(&old_rgroup->ref, release_res_group);
+}
+
+/*
+ * Set resource group of the task associated with pid to rgroup.
+ * returns 0 on success, -errno on error.
+ */
+int set_res_group(pid_t pid, struct resource_group *rgroup)
+{
+ int rc = 0;
+ struct task_struct *tsk;
+
+ read_lock(&tasklist_lock);
+ tsk = find_task_by_pid(pid);
+ if (tsk == NULL) {
+ read_unlock(&tasklist_lock);
+ return -ESRCH; /* pid not found */
+ }
+ get_task_struct(tsk);
+ read_unlock(&tasklist_lock);
+
+ /* Check permissions */
+ if ((!capable(CAP_SYS_NICE)) &&
+ (!capable(CAP_SYS_RESOURCE)) && (current->user != tsk->user))
+ rc = -EPERM;
+ else {
+ kref_get(&rgroup->ref);
+ __set_res_group(tsk, rgroup);
+ }
+ put_task_struct(tsk);
+ return rc;
+}
+EXPORT_SYMBOL_GPL(set_res_group);
Index: linux-2617-rc3/kernel/res_group/Makefile
===================================================================
--- linux-2617-rc3.orig/kernel/res_group/Makefile 2006-04-27 09:22:14.000000000 -0700
+++ linux-2617-rc3/kernel/res_group/Makefile 2006-04-27 09:22:16.000000000 -0700
@@ -1 +1 @@
-obj-y = res_group.o shares.o
+obj-y = res_group.o shares.o task.o
Index: linux-2617-rc3/kernel/res_group/res_group.c
===================================================================
--- linux-2617-rc3.orig/kernel/res_group/res_group.c 2006-04-27 09:22:14.000000000 -0700
+++ linux-2617-rc3/kernel/res_group/res_group.c 2006-04-27 09:22:16.000000000 -0700
@@ -251,6 +251,27 @@ static int add_controller(struct res_con
return ret;
}
/*
+ * Helper function to move all tasks in a resource group to/from the
+ * registering/unregistering resource controller.
+ *
+ * Assumes ctlr is valid and rgroup is initialized with resource
+ * controller's shares.
+ */
+static void move_tasks(struct resource_group *rgroup,
+ struct res_controller *ctlr,
+ struct res_shares *from, struct res_shares *to)
+{
+ struct task_struct *tsk;
+
+ if (!ctlr->move_task)
+ return;
+ spin_lock(&rgroup->group_lock);
+ list_for_each_entry(tsk, &rgroup->task_list, member_list)
+ ctlr->move_task(tsk, from, to);
+ spin_unlock(&rgroup->group_lock);
+}
+
+/*
* Interface for registering a resource controller.
*
* Returns the 0 on success, -errno for failure.
@@ -287,6 +308,8 @@ int register_controller(struct res_contr
kref_get(&rgroup->ref);
read_unlock(&res_group_lock);
do_alloc_shares_struct(rgroup, ctlr);
+ move_tasks(rgroup, ctlr, NO_SHARE,
+ rgroup->shares[ctlr->ctlr_id]);
if (prev_rgroup)
kref_put(&prev_rgroup->ref, release_res_group);
prev_rgroup = rgroup;
@@ -333,6 +356,8 @@ int unregister_controller(struct res_con
list_for_each_entry_reverse(rgroup, &res_groups, group_list) {
kref_get(&rgroup->ref);
read_unlock(&res_group_lock);
+ move_tasks(rgroup, ctlr, rgroup->shares[ctlr->ctlr_id],
+ NO_SHARE);
do_free_shares_struct(rgroup, ctlr);
if (prev_rgroup)
kref_put(&prev_rgroup->ref, release_res_group);
Index: linux-2617-rc3/kernel/res_group/local.h
===================================================================
--- linux-2617-rc3.orig/kernel/res_group/local.h 2006-04-27 09:22:14.000000000 -0700
+++ linux-2617-rc3/kernel/res_group/local.h 2006-04-27 09:22:16.000000000 -0700
@@ -18,3 +18,4 @@ extern int set_controller_shares(struct
extern void set_shares_to_default(struct resource_group *,
struct res_controller *);
extern void res_group_teardown(void);
+extern int set_res_group(pid_t, struct resource_group *);