7 files changed, 241 insertions, 0 deletions

diff --git a/Documentation/accounting/cgroupstats.txt b/Documentation/accounting/cgroupstats.txt
new file mode 100644
index 000000000000..eda40fd39cad
--- /dev/null
+++ b/Documentation/accounting/cgroupstats.txt
@@ -0,0 +1,27 @@
+Control Groupstats is inspired by the discussion at
+http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as
+suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263.
+
+Per cgroup statistics infrastructure re-uses code from the taskstats
+interface. A new set of cgroup operations are registered with commands
+and attributes specific to cgroups. It should be very easy to
+extend per cgroup statistics, by adding members to the cgroupstats
+structure.
+
+The current model for cgroupstats is a pull, a push model (to post
+statistics on interesting events), should be very easy to add. Currently
+user space requests for statistics by passing the cgroup path.
+Statistics about the state of all the tasks in the cgroup is returned to
+user space.
+
+NOTE: We currently rely on delay accounting for extracting information
+about tasks blocked on I/O. If CONFIG_TASK_DELAY_ACCT is disabled, this
+information will not be available.
+
+To extract cgroup statistics a utility very similar to getdelays.c
+has been developed, the sample output of the utility is shown below
+
+~/balbir/cgroupstats # ./getdelays  -C "/cgroup/a"
+sleeping 1, blocked 0, running 1, stopped 0, uninterruptible 0
+~/balbir/cgroupstats # ./getdelays  -C "/cgroup"
+sleeping 155, blocked 0, running 1, stopped 0, uninterruptible 2
diff --git a/include/linux/Kbuild b/include/linux/Kbuild
index 7ac8303c8471..e3ffd14a3f0b 100644
--- a/include/linux/Kbuild
+++ b/include/linux/Kbuild
@@ -47,6 +47,7 @@ header-y += coda_psdev.h
 header-y += coff.h
 header-y += comstats.h
 header-y += const.h
+header-y += cgroupstats.h
 header-y += cycx_cfm.h
 header-y += dlm_device.h
 header-y += dlm_netlink.h
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 9e9b7efa180b..87479328d46d 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -13,6 +13,7 @@
 #include <linux/cpumask.h>
 #include <linux/nodemask.h>
 #include <linux/rcupdate.h>
+#include <linux/cgroupstats.h>
 
 #ifdef CONFIG_CGROUPS
 
@@ -29,6 +30,8 @@ extern void cgroup_fork(struct task_struct *p);
 extern void cgroup_fork_callbacks(struct task_struct *p);
 extern void cgroup_post_fork(struct task_struct *p);
 extern void cgroup_exit(struct task_struct *p, int run_callbacks);
+extern int cgroupstats_build(struct cgroupstats *stats,
+                                struct dentry *dentry);
 
 extern struct file_operations proc_cgroup_operations;
 
@@ -313,6 +316,11 @@ static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
 
 static inline void cgroup_lock(void) {}
 static inline void cgroup_unlock(void) {}
+static inline int cgroupstats_build(struct cgroupstats *stats,
+                                        struct dentry *dentry)
+{
+        return -EINVAL;
+}
 
 #endif /* !CONFIG_CGROUPS */
 
diff --git a/include/linux/cgroupstats.h b/include/linux/cgroupstats.h
new file mode 100644
index 000000000000..4f53abf6855d
--- /dev/null
+++ b/include/linux/cgroupstats.h
@@ -0,0 +1,70 @@
+/* cgroupstats.h - exporting per-cgroup statistics
+ *
+ * Copyright IBM Corporation, 2007
+ * Author Balbir Singh <balbir@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#ifndef _LINUX_CGROUPSTATS_H
+#define _LINUX_CGROUPSTATS_H
+
+#include <linux/taskstats.h>
+
+/*
+ * Data shared between user space and kernel space on a per cgroup
+ * basis. This data is shared using taskstats.
+ *
+ * Most of these states are derived by looking at the task->state value
+ * For the nr_io_wait state, a flag in the delay accounting structure
+ * indicates that the task is waiting on IO
+ *
+ * Each member is aligned to a 8 byte boundary.
+ */
+struct cgroupstats {
+        __u64   nr_sleeping;            /* Number of tasks sleeping */
+        __u64   nr_running;             /* Number of tasks running */
+        __u64   nr_stopped;             /* Number of tasks in stopped state */
+        __u64   nr_uninterruptible;     /* Number of tasks in uninterruptible */
+                                        /* state */
+        __u64   nr_io_wait;             /* Number of tasks waiting on IO */
+};
+
+/*
+ * Commands sent from userspace
+ * Not versioned. New commands should only be inserted at the enum's end
+ * prior to __CGROUPSTATS_CMD_MAX
+ */
+
+enum {
+        CGROUPSTATS_CMD_UNSPEC = __TASKSTATS_CMD_MAX,   /* Reserved */
+        CGROUPSTATS_CMD_GET,            /* user->kernel request/get-response */
+        CGROUPSTATS_CMD_NEW,            /* kernel->user event */
+        __CGROUPSTATS_CMD_MAX,
+};
+
+#define CGROUPSTATS_CMD_MAX (__CGROUPSTATS_CMD_MAX - 1)
+
+enum {
+        CGROUPSTATS_TYPE_UNSPEC = 0,    /* Reserved */
+        CGROUPSTATS_TYPE_CGROUP_STATS,  /* contains name + stats */
+        __CGROUPSTATS_TYPE_MAX,
+};
+
+#define CGROUPSTATS_TYPE_MAX (__CGROUPSTATS_TYPE_MAX - 1)
+
+enum {
+        CGROUPSTATS_CMD_ATTR_UNSPEC = 0,
+        CGROUPSTATS_CMD_ATTR_FD,
+        __CGROUPSTATS_CMD_ATTR_MAX,
+};
+
+#define CGROUPSTATS_CMD_ATTR_MAX (__CGROUPSTATS_CMD_ATTR_MAX - 1)
+
+#endif /* _LINUX_CGROUPSTATS_H */
diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
index 55d1ca5e60f5..ab94bc083558 100644
--- a/include/linux/delayacct.h
+++ b/include/linux/delayacct.h
@@ -26,6 +26,7 @@
  * Used to set current->delays->flags
  */
 #define DELAYACCT_PF_SWAPIN     0x00000001      /* I am doing a swapin */
+#define DELAYACCT_PF_BLKIO      0x00000002      /* I am waiting on IO */
 
 #ifdef CONFIG_TASK_DELAY_ACCT
 
@@ -39,6 +40,14 @@ extern void __delayacct_blkio_end(void);
 extern int __delayacct_add_tsk(struct taskstats *, struct task_struct *);
 extern __u64 __delayacct_blkio_ticks(struct task_struct *);
 
+static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
+{
+        if (p->delays)
+                return (p->delays->flags & DELAYACCT_PF_BLKIO);
+        else
+                return 0;
+}
+
 static inline void delayacct_set_flag(int flag)
 {
         if (current->delays)
@@ -71,6 +80,7 @@ static inline void delayacct_tsk_free(struct task_struct *tsk)
 
 static inline void delayacct_blkio_start(void)
 {
+        delayacct_set_flag(DELAYACCT_PF_BLKIO);
         if (current->delays)
                 __delayacct_blkio_start();
 }
@@ -79,6 +89,7 @@ static inline void delayacct_blkio_end(void)
 {
         if (current->delays)
                 __delayacct_blkio_end();
+        delayacct_clear_flag(DELAYACCT_PF_BLKIO);
 }
 
 static inline int delayacct_add_tsk(struct taskstats *d,
@@ -116,6 +127,8 @@ static inline int delayacct_add_tsk(struct taskstats *d,
 { return 0; }
 static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
 { return 0; }
+static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
+{ return 0; }
 #endif /* CONFIG_TASK_DELAY_ACCT */
 
 #endif
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index d65a1246829f..ca38db223f84 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -44,6 +44,9 @@
 #include <linux/string.h>
 #include <linux/sort.h>
 #include <linux/kmod.h>
+#include <linux/delayacct.h>
+#include <linux/cgroupstats.h>
+
 #include <asm/atomic.h>
 
 static DEFINE_MUTEX(cgroup_mutex);
@@ -1766,6 +1769,58 @@ static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cont)
         return n;
 }
 
+/**
+ * Build and fill cgroupstats so that taskstats can export it to user
+ * space.
+ *
+ * @stats: cgroupstats to fill information into
+ * @dentry: A dentry entry belonging to the cgroup for which stats have
+ * been requested.
+ */
+int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
+{
+        int ret = -EINVAL;
+        struct cgroup *cont;
+        struct cgroup_iter it;
+        struct task_struct *tsk;
+        /*
+         * Validate dentry by checking the superblock operations
+         */
+        if (dentry->d_sb->s_op != &cgroup_ops)
+                 goto err;
+
+        ret = 0;
+        cont = dentry->d_fsdata;
+        rcu_read_lock();
+
+        cgroup_iter_start(cont, &it);
+        while ((tsk = cgroup_iter_next(cont, &it))) {
+                switch (tsk->state) {
+                case TASK_RUNNING:
+                        stats->nr_running++;
+                        break;
+                case TASK_INTERRUPTIBLE:
+                        stats->nr_sleeping++;
+                        break;
+                case TASK_UNINTERRUPTIBLE:
+                        stats->nr_uninterruptible++;
+                        break;
+                case TASK_STOPPED:
+                        stats->nr_stopped++;
+                        break;
+                default:
+                        if (delayacct_is_task_waiting_on_io(tsk))
+                                stats->nr_io_wait++;
+                        break;
+                }
+        }
+        cgroup_iter_end(cont, &it);
+
+        rcu_read_unlock();
+err:
+        return ret;
+}
+
 static int cmppid(const void *a, const void *b)
 {
         return *(pid_t *)a - *(pid_t *)b;
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 7d4d7f9c1bb2..9f360f68aad6 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -22,6 +22,10 @@
 #include <linux/delayacct.h>
 #include <linux/cpumask.h>
 #include <linux/percpu.h>
+#include <linux/cgroupstats.h>
+#include <linux/cgroup.h>
+#include <linux/fs.h>
+#include <linux/file.h>
 #include <net/genetlink.h>
 #include <asm/atomic.h>
 
@@ -49,6 +53,11 @@ __read_mostly = {
         [TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
         [TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};
 
+static struct nla_policy
+cgroupstats_cmd_get_policy[CGROUPSTATS_CMD_ATTR_MAX+1] __read_mostly = {
+        [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
+};
+
 struct listener {
         struct list_head list;
         pid_t pid;
@@ -372,6 +381,51 @@ err:
         return NULL;
 }
 
+static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
+{
+        int rc = 0;
+        struct sk_buff *rep_skb;
+        struct cgroupstats *stats;
+        struct nlattr *na;
+        size_t size;
+        u32 fd;
+        struct file *file;
+        int fput_needed;
+
+        na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
+        if (!na)
+                return -EINVAL;
+
+        fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
+        file = fget_light(fd, &fput_needed);
+        if (file) {
+                size = nla_total_size(sizeof(struct cgroupstats));
+
+                rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
+                                        size);
+                if (rc < 0)
+                        goto err;
+
+                na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
+                                        sizeof(struct cgroupstats));
+                stats = nla_data(na);
+                memset(stats, 0, sizeof(*stats));
+
+                rc = cgroupstats_build(stats, file->f_dentry);
+                if (rc < 0)
+                        goto err;
+
+                fput_light(file, fput_needed);
+                return send_reply(rep_skb, info->snd_pid);
+        }
+
+err:
+        if (file)
+                fput_light(file, fput_needed);
+        nlmsg_free(rep_skb);
+        return rc;
+}
+
 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 {
         int rc = 0;
@@ -522,6 +576,12 @@ static struct genl_ops taskstats_ops = {
         .policy         = taskstats_cmd_get_policy,
 };
 
+static struct genl_ops cgroupstats_ops = {
+        .cmd            = CGROUPSTATS_CMD_GET,
+        .doit           = cgroupstats_user_cmd,
+        .policy         = cgroupstats_cmd_get_policy,
+};
+
 /* Needed early in initialization */
 void __init taskstats_init_early(void)
 {
@@ -546,8 +606,15 @@ static int __init taskstats_init(void)
         if (rc < 0)
                 goto err;
 
+        rc = genl_register_ops(&family, &cgroupstats_ops);
+        if (rc < 0)
+                goto err_cgroup_ops;
+
         family_registered = 1;
+        printk("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
         return 0;
+err_cgroup_ops:
+        genl_unregister_ops(&family, &taskstats_ops);
 err:
         genl_unregister_family(&family);
         return rc;