Task Control Groups: make cpusets a client of cgroups

Remove the filesystem support logic from the cpusets system and makes cpusets
a cgroup subsystem

The "cpuset" filesystem becomes a dummy filesystem; attempts to mount it get
passed through to the cgroup filesystem with the appropriate options to
emulate the old cpuset filesystem behaviour.

Signed-off-by: Paul Menage <menage@google.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/cpusets.txt

@@ -7,6 +7,7 @@ Written by Simon.Derr@bull.net
 Portions Copyright (c) 2004-2006 Silicon Graphics, Inc.
 Modified by Paul Jackson <pj@sgi.com>
 Modified by Christoph Lameter <clameter@sgi.com>
+Modified by Paul Menage <menage@google.com>
 
 CONTENTS:
 =========
@@ -16,10 +17,9 @@ CONTENTS:
   1.2 Why are cpusets needed ?
   1.3 How are cpusets implemented ?
   1.4 What are exclusive cpusets ?
-  1.5 What does notify_on_release do ?
-  1.6 What is memory_pressure ?
-  1.7 What is memory spread ?
-  1.8 How do I use cpusets ?
+  1.5 What is memory_pressure ?
+  1.6 What is memory spread ?
+  1.7 How do I use cpusets ?
 2. Usage Examples and Syntax
   2.1 Basic Usage
   2.2 Adding/removing cpus
@@ -44,18 +44,19 @@ hierarchy visible in a virtual file system.  These are the essential
 hooks, beyond what is already present, required to manage dynamic
 job placement on large systems.
 
-Each task has a pointer to a cpuset.  Multiple tasks may reference
-the same cpuset.  Requests by a task, using the sched_setaffinity(2)
-system call to include CPUs in its CPU affinity mask, and using the
-mbind(2) and set_mempolicy(2) system calls to include Memory Nodes
-in its memory policy, are both filtered through that tasks cpuset,
-filtering out any CPUs or Memory Nodes not in that cpuset.  The
-scheduler will not schedule a task on a CPU that is not allowed in
-its cpus_allowed vector, and the kernel page allocator will not
-allocate a page on a node that is not allowed in the requesting tasks
-mems_allowed vector.
-
-User level code may create and destroy cpusets by name in the cpuset
+Cpusets use the generic cgroup subsystem described in
+Documentation/cgroup.txt.
+
+Requests by a task, using the sched_setaffinity(2) system call to
+include CPUs in its CPU affinity mask, and using the mbind(2) and
+set_mempolicy(2) system calls to include Memory Nodes in its memory
+policy, are both filtered through that tasks cpuset, filtering out any
+CPUs or Memory Nodes not in that cpuset.  The scheduler will not
+schedule a task on a CPU that is not allowed in its cpus_allowed
+vector, and the kernel page allocator will not allocate a page on a
+node that is not allowed in the requesting tasks mems_allowed vector.
+
+User level code may create and destroy cpusets by name in the cgroup
 virtual file system, manage the attributes and permissions of these
 cpusets and which CPUs and Memory Nodes are assigned to each cpuset,
 specify and query to which cpuset a task is assigned, and list the
@@ -115,7 +116,7 @@ Cpusets extends these two mechanisms as follows:
  - Cpusets are sets of allowed CPUs and Memory Nodes, known to the
    kernel.
  - Each task in the system is attached to a cpuset, via a pointer
-   in the task structure to a reference counted cpuset structure.
+   in the task structure to a reference counted cgroup structure.
  - Calls to sched_setaffinity are filtered to just those CPUs
    allowed in that tasks cpuset.
  - Calls to mbind and set_mempolicy are filtered to just
@@ -145,15 +146,10 @@ into the rest of the kernel, none in performance critical paths:
  - in page_alloc.c, to restrict memory to allowed nodes.
  - in vmscan.c, to restrict page recovery to the current cpuset.
 
-In addition a new file system, of type "cpuset" may be mounted,
-typically at /dev/cpuset, to enable browsing and modifying the cpusets
-presently known to the kernel.  No new system calls are added for
-cpusets - all support for querying and modifying cpusets is via
-this cpuset file system.
-
-Each task under /proc has an added file named 'cpuset', displaying
-the cpuset name, as the path relative to the root of the cpuset file
-system.
+You should mount the "cgroup" filesystem type in order to enable
+browsing and modifying the cpusets presently known to the kernel.  No
+new system calls are added for cpusets - all support for querying and
+modifying cpusets is via this cpuset file system.
 
 The /proc/<pid>/status file for each task has two added lines,
 displaying the tasks cpus_allowed (on which CPUs it may be scheduled)
@@ -163,16 +159,15 @@ in the format seen in the following example:
   Cpus_allowed:   ffffffff,ffffffff,ffffffff,ffffffff
   Mems_allowed:   ffffffff,ffffffff
 
-Each cpuset is represented by a directory in the cpuset file system
-containing the following files describing that cpuset:
+Each cpuset is represented by a directory in the cgroup file system
+containing (on top of the standard cgroup files) the following
+files describing that cpuset:
 
  - cpus: list of CPUs in that cpuset
  - mems: list of Memory Nodes in that cpuset
  - memory_migrate flag: if set, move pages to cpusets nodes
  - cpu_exclusive flag: is cpu placement exclusive?
  - mem_exclusive flag: is memory placement exclusive?
- - tasks: list of tasks (by pid) attached to that cpuset
- - notify_on_release flag: run /sbin/cpuset_release_agent on exit?
  - memory_pressure: measure of how much paging pressure in cpuset
 
 In addition, the root cpuset only has the following file:
@@ -237,21 +232,7 @@ such as requests from interrupt handlers, is allowed to be taken
 outside even a mem_exclusive cpuset.
 
 
-1.5 What does notify_on_release do ?
-------------------------------------
-
-If the notify_on_release flag is enabled (1) in a cpuset, then whenever
-the last task in the cpuset leaves (exits or attaches to some other
-cpuset) and the last child cpuset of that cpuset is removed, then
-the kernel runs the command /sbin/cpuset_release_agent, supplying the
-pathname (relative to the mount point of the cpuset file system) of the
-abandoned cpuset.  This enables automatic removal of abandoned cpusets.
-The default value of notify_on_release in the root cpuset at system
-boot is disabled (0).  The default value of other cpusets at creation
-is the current value of their parents notify_on_release setting.
-
-
-1.6 What is memory_pressure ?
+1.5 What is memory_pressure ?
 -----------------------------
 The memory_pressure of a cpuset provides a simple per-cpuset metric
 of the rate that the tasks in a cpuset are attempting to free up in
@@ -308,7 +289,7 @@ the tasks in the cpuset, in units of reclaims attempted per second,
 times 1000.
 
 
-1.7 What is memory spread ?
+1.6 What is memory spread ?
 ---------------------------
 There are two boolean flag files per cpuset that control where the
 kernel allocates pages for the file system buffers and related in
@@ -379,7 +360,7 @@ data set, the memory allocation across the nodes in the jobs cpuset
 can become very uneven.
 
 
-1.8 How do I use cpusets ?
+1.7 How do I use cpusets ?
 --------------------------
 
 In order to minimize the impact of cpusets on critical kernel
@@ -469,7 +450,7 @@ than stress the kernel.
 To start a new job that is to be contained within a cpuset, the steps are:
 
  1) mkdir /dev/cpuset
- 2) mount -t cpuset none /dev/cpuset
+ 2) mount -t cgroup -ocpuset cpuset /dev/cpuset
  3) Create the new cpuset by doing mkdir's and write's (or echo's) in
     the /dev/cpuset virtual file system.
  4) Start a task that will be the "founding father" of the new job.
@@ -481,7 +462,7 @@ For example, the following sequence of commands will setup a cpuset
 named "Charlie", containing just CPUs 2 and 3, and Memory Node 1,
 and then start a subshell 'sh' in that cpuset:
 
-  mount -t cpuset none /dev/cpuset
+  mount -t cgroup -ocpuset cpuset /dev/cpuset
   cd /dev/cpuset
   mkdir Charlie
   cd Charlie
@@ -513,7 +494,7 @@ Creating, modifying, using the cpusets can be done through the cpuset
 virtual filesystem.
 
 To mount it, type:
-# mount -t cpuset none /dev/cpuset
+# mount -t cgroup -o cpuset cpuset /dev/cpuset
 
 Then under /dev/cpuset you can find a tree that corresponds to the
 tree of the cpusets in the system. For instance, /dev/cpuset
@@ -556,6 +537,18 @@ To remove a cpuset, just use rmdir:
 This will fail if the cpuset is in use (has cpusets inside, or has
 processes attached).
 
+Note that for legacy reasons, the "cpuset" filesystem exists as a
+wrapper around the cgroup filesystem.
+
+The command
+
+mount -t cpuset X /dev/cpuset
+
+is equivalent to
+
+mount -t cgroup -ocpuset X /dev/cpuset
+echo "/sbin/cpuset_release_agent" > /dev/cpuset/release_agent
+
 2.2 Adding/removing cpus
 ------------------------
 

fs/proc/base.c

@@ -2131,7 +2131,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_SCHEDSTATS
 	INF("schedstat",  S_IRUGO, pid_schedstat),
 #endif
-#ifdef CONFIG_CPUSETS
+#ifdef CONFIG_PROC_PID_CPUSET
 	REG("cpuset",     S_IRUGO, cpuset),
 #endif
 #ifdef CONFIG_CGROUPS
@@ -2420,7 +2420,7 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_SCHEDSTATS
 	INF("schedstat", S_IRUGO, pid_schedstat),
 #endif
-#ifdef CONFIG_CPUSETS
+#ifdef CONFIG_PROC_PID_CPUSET
 	REG("cpuset",    S_IRUGO, cpuset),
 #endif
 #ifdef CONFIG_CGROUPS

include/linux/cgroup_subsys.h

@@ -7,4 +7,10 @@
 
 /* */
 
+#ifdef CONFIG_CPUSETS
+SUBSYS(cpuset)
+#endif
+
+/* */
+
 /* */

include/linux/cpuset.h

@@ -11,6 +11,7 @@
 #include <linux/sched.h>
 #include <linux/cpumask.h>
 #include <linux/nodemask.h>
+#include <linux/cgroup.h>
 
 #ifdef CONFIG_CPUSETS
 
@@ -19,8 +20,6 @@ extern int number_of_cpusets;	/* How many cpusets are defined in system? */
 extern int cpuset_init_early(void);
 extern int cpuset_init(void);
 extern void cpuset_init_smp(void);
-extern void cpuset_fork(struct task_struct *p);
-extern void cpuset_exit(struct task_struct *p);
 extern cpumask_t cpuset_cpus_allowed(struct task_struct *p);
 extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
 #define cpuset_current_mems_allowed (current->mems_allowed)
@@ -76,13 +75,13 @@ static inline int cpuset_do_slab_mem_spread(void)
 
 extern void cpuset_track_online_nodes(void);
 
+extern int current_cpuset_is_being_rebound(void);
+
 #else /* !CONFIG_CPUSETS */
 
 static inline int cpuset_init_early(void) { return 0; }
 static inline int cpuset_init(void) { return 0; }
 static inline void cpuset_init_smp(void) {}
-static inline void cpuset_fork(struct task_struct *p) {}
-static inline void cpuset_exit(struct task_struct *p) {}
 
 static inline cpumask_t cpuset_cpus_allowed(struct task_struct *p)
 {
@@ -148,6 +147,11 @@ static inline int cpuset_do_slab_mem_spread(void)
 
 static inline void cpuset_track_online_nodes(void) {}
 
+static inline int current_cpuset_is_being_rebound(void)
+{
+	return 0;
+}
+
 #endif /* !CONFIG_CPUSETS */
 
 #endif /* _LINUX_CPUSET_H */

include/linux/mempolicy.h

@@ -148,14 +148,6 @@ extern void mpol_rebind_task(struct task_struct *tsk,
 					const nodemask_t *new);
 extern void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new);
 extern void mpol_fix_fork_child_flag(struct task_struct *p);
-#define set_cpuset_being_rebound(x) (cpuset_being_rebound = (x))
-
-#ifdef CONFIG_CPUSETS
-#define current_cpuset_is_being_rebound() \
-				(cpuset_being_rebound == current->cpuset)
-#else
-#define current_cpuset_is_being_rebound() 0
-#endif
 
 extern struct mempolicy default_policy;
 extern struct zonelist *huge_zonelist(struct vm_area_struct *vma,
@@ -173,8 +165,6 @@ static inline void check_highest_zone(enum zone_type k)
 int do_migrate_pages(struct mm_struct *mm,
 	const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags);
 
-extern void *cpuset_being_rebound;	/* Trigger mpol_copy vma rebind */
-
 #else
 
 struct mempolicy {};
@@ -248,8 +238,6 @@ static inline void mpol_fix_fork_child_flag(struct task_struct *p)
 {
 }
 
-#define set_cpuset_being_rebound(x) do {} while (0)
-
 static inline struct zonelist *huge_zonelist(struct vm_area_struct *vma,
  		unsigned long addr, gfp_t gfp_flags, struct mempolicy **mpol)
 {

include/linux/sched.h

@@ -756,8 +756,6 @@ static inline int above_background_load(void)
 }
 
 struct io_context;			/* See blkdev.h */
-struct cpuset;
-
 #define NGROUPS_SMALL		32
 #define NGROUPS_PER_BLOCK	((int)(PAGE_SIZE / sizeof(gid_t)))
 struct group_info {
@@ -1125,7 +1123,6 @@ struct task_struct {
 	short il_next;
 #endif
 #ifdef CONFIG_CPUSETS
-	struct cpuset *cpuset;
 	nodemask_t mems_allowed;
 	int cpuset_mems_generation;
 	int cpuset_mem_spread_rotor;

init/Kconfig

@@ -280,7 +280,7 @@ config CGROUPS
 
 config CPUSETS
 	bool "Cpuset support"
-	depends on SMP
+	depends on SMP && CGROUPS
 	help
 	  This option will let you create and manage CPUSETs which
 	  allow dynamically partitioning a system into sets of CPUs and
@@ -330,6 +330,11 @@ config SYSFS_DEPRECATED
 	  If you are using a distro that was released in 2006 or later,
 	  it should be safe to say N here.
 
+config PROC_PID_CPUSET
+	bool "Include legacy /proc/<pid>/cpuset file"
+	depends on CPUSETS
+	default y
+
 config RELAY
 	bool "Kernel->user space relay support (formerly relayfs)"
 	help