Re: schedstat-2.6.8.1 [was: Re: 2.6.9-rc1-mm1]

Rick Lindsley
2004-09-08T07:12:42Z

I wrote:

A schedstats patch for 2.6.8.1 is available at
http://eaglet.rain.com/rick/linux/schedstat/patches/schedstat-2.6.8.1
or
http://oss.software.ibm.com/linux/patches/?patch_id=3D730

Rafael replied:

It does not compile for me on a UP system:

Mea culpa. This was fixed once but didn't propogate into my last patch.
Please try this patch instead.

diff -rupN linux-2.6.8.1/Documentation/sched-stats.txt linux-2.6.8.1-ss/Documentation/sched-stats.txt
--- linux-2.6.8.1/Documentation/sched-stats.txt 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.8.1-ss/Documentation/sched-stats.txt 2004-09-07 22:30:10.000000000 -0700
@@ -0,0 +1,150 @@
+Version 9 of schedstats introduces support for sched_domains, which
+hit the mainline kernel in 2.6.7. Some counters make more sense to be
+per-runqueue; other to be per-domain.
+
+In version 9 of schedstat, there is at least one level of domain
+statistics for each cpu listed, and there may well be more than one
+domain. Domains have no particular names in this implementation, but
+the highest numbered one typically arbitrates balancing across all the
+cpus on the machine, while domain0 is the most tightly focused domain,
+sometimes balancing only between pairs of cpus. At this time, there
+are no architectures which need more than three domain levels. The first
+field in the domain stats is a bit map indicating which cpus are affected
+by that domain.
+
+These fields are counters, and only increment. Programs which make use
+of these will need to start with a baseline observation and then calculate
+the change in the counters at each subsequent observation. A perl script
+which does this for many of the fields is available at
+
+ http://eaglet.rain.com/rick/linux/schedstat/
+
+Note that any such script will necessarily be version-specific, as the main
+reason to change versions is changes in the output format. For those wishing
+to write their own scripts, the fields are described here.
+
+CPU statistics
+--------------
+cpu<N> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
+
+NOTE: In the sched_yield() statistics, the active queue is considered empty
+ if it has only one process in it, since obviously the process calling
+ sched_yield() is that process.
+
+First four fields are sched_yield() statistics:
+ 1) # of times both the active and the expired queue were empty
+ 2) # of times just the active queue was empty
+ 3) # of times just the expired queue was empty
+ 4) # of times sched_yield() was called
+
+Next four are schedule() statistics:
+ 5) # of times the active queue had at least one other process on it.
+ 6) # of times we switched to the expired queue and reused it
+ 7) # of times schedule() was called
+ 8) # of times schedule() left the processor idle
+
+Next four are active_load_balance() statistics:
+ 9) # of times active_load_balance() was called
+ 10) # of times active_load_balance() caused this cpu to gain a task
+ 11) # of times active_load_balance() caused this cpu to lose a task
+ 12) # of times active_load_balance() tried to move a task and failed
+
+Next three are try_to_wake_up() statistics:
+ 13) # of times try_to_wake_up() was called
+ 14) # of times try_to_wake_up() successfully moved the awakening task
+ 15) # of times try_to_wake_up() attempted to move the awakening task
+
+Next two are wake_up_forked_thread() statistics:
+ 16) # of times wake_up_forked_thread() was called
+ 17) # of times wake_up_forked_thread() successfully moved the forked task
+
+Next one is a sched_migrate_task() statistic:
+ 18) # of times sched_migrate_task() was called
+
+Next one is a sched_balance_exec() statistic:
+ 19) # of times sched_balance_exec() was called
+
+Next three are statistics describing scheduling latency:
+ 20) sum of all time spent running by tasks on this processor (in ms)
+ 21) sum of all time spent waiting to run by tasks on this processor (in ms)
+ 22) # of tasks (not necessarily unique) given to the processor
+
+The last six are statistics dealing with pull_task():
+ 23) # of times pull_task() moved a task to this cpu when newly idle
+ 24) # of times pull_task() stole a task from this cpu when another cpu
+ was newly idle
+ 25) # of times pull_task() moved a task to this cpu when idle
+ 26) # of times pull_task() stole a task from this cpu when another cpu
+ was idle
+ 27) # of times pull_task() moved a task to this cpu when busy
+ 28) # of times pull_task() stole a task from this cpu when another cpu
+ was busy
+
+
+Domain statistics
+-----------------
+One of these is produced per domain for each cpu described.
+
+domain<N> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
+
+The first field is a bit mask indicating what cpus this domain operates over.
+
+The next fifteen are a variety of load_balance() statistics:
+
+ 1) # of times in this domain load_balance() was called when the cpu
+ was idle
+ 2) # of times in this domain load_balance() was called when the cpu
+ was busy
+ 3) # of times in this domain load_balance() was called when the cpu
+ was just becoming idle
+ 4) # of times in this domain load_balance() tried to move one or more
+ tasks and failed, when the cpu was idle
+ 5) # of times in this domain load_balance() tried to move one or more
+ tasks and failed, when the cpu was busy
+ 6) # of times in this domain load_balance() tried to move one or more
+ tasks and failed, when the cpu was just becoming idle
+ 7) sum of imbalances discovered (if any) with each call to
+ load_balance() in this domain when the cpu was idle
+ 8) sum of imbalances discovered (if any) with each call to
+ load_balance() in this domain when the cpu was busy
+ 9) sum of imbalances discovered (if any) with each call to
+ load_balance() in this domain when the cpu was just becoming idle
+ 10) # of times in this domain load_balance() was called but did not find
+ a busier queue while the cpu was idle
+ 11) # of times in this domain load_balance() was called but did not find
+ a busier queue while the cpu was busy
+ 12) # of times in this domain load_balance() was called but did not find
+ a busier queue while the cpu was just becoming idle
+ 13) # of times in this domain a busier queue was found while the cpu was
+ idle but no busier group was found
+ 14) # of times in this domain a busier queue was found while the cpu was
+ busy but no busier group was found
+ 15) # of times in this domain a busier queue was found while the cpu was
+ just becoming idle but no busier group was found
+
+Next two are sched_balance_exec() statistics:
+ 17) # of times in this domain sched_balance_exec() successfully pushed
+ a task to a new cpu
+ 18) # of times in this domain sched_balance_exec() tried but failed to
+ push a task to a new cpu
+
+Next two are try_to_wake_up() statistics:
+ 19) # of times in this domain try_to_wake_up() tried to move a task based
+ on affinity and cache warmth
+ 20) # of times in this domain try_to_wake_up() tried to move a task based
+ on load balancing
+
+
+/proc/<pid>/stat
+----------------
+schedstats also changes the stat output of individual processes to
+include some of the same information on a per-process level, obtainable
+from /proc/<pid>/stat. Three new fields correlating to fields 20, 21,
+and 22 in the CPU fields, are tacked on to the end but apply only for
+that process.
+
+A program could be easily written to make use of these extra fields to
+report on how well a particular process or set of processes is faring
+under the scheduler's policies. A simple version of such a program is
+available at
+ http://eaglet.rain.com/rick/linux/schedstat/v9/latency.c
diff -rupN linux-2.6.8.1/arch/i386/Kconfig linux-2.6.8.1-ss/arch/i386/Kconfig
--- linux-2.6.8.1/arch/i386/Kconfig 2004-08-14 03:54:50.000000000 -0700
+++ linux-2.6.8.1-ss/arch/i386/Kconfig 2004-09-07 22:30:10.000000000 -0700
@@ -1298,6 +1298,19 @@ config 4KSTACKS
on the VM subsystem for higher order allocations. This option
will also use IRQ stacks to compensate for the reduced stackspace.

+config SCHEDSTATS
+ bool "Collect scheduler statistics"
+ depends on PROC_FS
+ default y
+ help
+ If you say Y here, additional code will be inserted into the
+ scheduler and related routines to collect statistics about
+ scheduler behavior and provide them in /proc/schedstat. These
+ stats may be useful for both tuning and debugging the scheduler
+ If you aren't debugging the scheduler or trying to tune a specific
+ application, you can say N to avoid the very slight overhead
+ this adds.
+
config X86_FIND_SMP_CONFIG
bool
depends on X86_LOCAL_APIC || X86_VOYAGER
diff -rupN linux-2.6.8.1/arch/ppc/Kconfig linux-2.6.8.1-ss/arch/ppc/Kconfig
--- linux-2.6.8.1/arch/ppc/Kconfig 2004-08-14 03:56:23.000000000 -0700
+++ linux-2.6.8.1-ss/arch/ppc/Kconfig 2004-09-07 22:30:10.000000000 -0700
@@ -1333,6 +1333,19 @@ config DEBUG_INFO
debug the kernel.
If you don't debug the kernel, you can say N.

+config SCHEDSTATS
+ bool "Collect scheduler statistics"
+ depends on PROC_FS
+ default y
+ help
+ If you say Y here, additional code will be inserted into the
+ scheduler and related routines to collect statistics about
+ scheduler behavior and provide them in /proc/schedstat. These
+ stats may be useful for both tuning and debugging the scheduler
+ If you aren't debugging the scheduler or trying to tune a specific
+ application, you can say N to avoid the very slight overhead
+ this adds.
+
config BOOTX_TEXT
bool "Support for early boot text console (BootX or OpenFirmware only)"
depends PPC_OF
diff -rupN linux-2.6.8.1/arch/ppc64/Kconfig linux-2.6.8.1-ss/arch/ppc64/Kconfig
--- linux-2.6.8.1/arch/ppc64/Kconfig 2004-08-14 03:55:33.000000000 -0700
+++ linux-2.6.8.1-ss/arch/ppc64/Kconfig 2004-09-07 22:30:10.000000000 -0700
@@ -424,6 +424,19 @@ config IRQSTACKS
for handling hard and soft interrupts. This can help avoid
overflowing the process kernel stacks.

+config SCHEDSTATS
+ bool "Collect scheduler statistics"
+ depends on PROC_FS
+ default y
+ help
+ If you say Y here, additional code will be inserted into the
+ scheduler and related routines to collect statistics about
+ scheduler behavior and provide them in /proc/schedstat. These
+ stats may be useful for both tuning and debugging the scheduler
+ If you aren't debugging the scheduler or trying to tune a specific
+ application, you can say N to avoid the very slight overhead
+ this adds.
+
config SPINLINE
bool "Inline spinlock code at each call site"
depends on SMP && !PPC_SPLPAR && !PPC_ISERIES
diff -rupN linux-2.6.8.1/arch/x86_64/Kconfig linux-2.6.8.1-ss/arch/x86_64/Kconfig
--- linux-2.6.8.1/arch/x86_64/Kconfig 2004-08-14 03:55:59.000000000 -0700
+++ linux-2.6.8.1-ss/arch/x86_64/Kconfig 2004-09-07 22:30:10.000000000 -0700
@@ -461,6 +461,19 @@ config DEBUG_INFO
Say Y here only if you plan to use gdb to debug the kernel.
Please note that this option requires new binutils.
If you don't debug the kernel, you can say N.
+
+config SCHEDSTATS
+ bool "Collect scheduler statistics"
+ depends on PROC_FS
+ default y
+ help
+ If you say Y here, additional code will be inserted into the
+ scheduler and related routines to collect statistics about
+ scheduler behavior and provide them in /proc/schedstat. These
+ stats may be useful for both tuning and debugging the scheduler
+ If you aren't debugging the scheduler or trying to tune a specific
+ application, you can say N to avoid the very slight overhead
+ this adds.

config FRAME_POINTER
bool "Compile the kernel with frame pointers"
diff -rupN linux-2.6.8.1/fs/proc/array.c linux-2.6.8.1-ss/fs/proc/array.c
--- linux-2.6.8.1/fs/proc/array.c 2004-08-14 03:55:34.000000000 -0700
+++ linux-2.6.8.1-ss/fs/proc/array.c 2004-09-07 22:30:10.000000000 -0700
@@ -358,9 +358,15 @@ int proc_pid_stat(struct task_struct *ta
/* Temporary variable needed for gcc-2.96 */
start_time = jiffies_64_to_clock_t(task->start_time - INITIAL_JIFFIES);

+#ifdef CONFIG_SCHEDSTATS
+ res = sprintf(buffer,"%d (%s) %c %d %d %d %d %d %lu %lu \
+%lu %lu %lu %lu %lu %ld %ld %ld %ld %d %ld %llu %lu %ld %lu %lu %lu %lu %lu \
+%lu %lu %lu %lu %lu %lu %lu %lu %d %d %lu %lu %lu %lu %lu\n",
+#else
res = sprintf(buffer,"%d (%s) %c %d %d %d %d %d %lu %lu \
%lu %lu %lu %lu %lu %ld %ld %ld %ld %d %ld %llu %lu %ld %lu %lu %lu %lu %lu \
%lu %lu %lu %lu %lu %lu %lu %lu %d %d %lu %lu\n",
+#endif
task->pid,
task->comm,
state,
@@ -405,7 +411,14 @@ int proc_pid_stat(struct task_struct *ta
task->exit_signal,
task_cpu(task),
task->rt_priority,
+#ifdef CONFIG_SCHEDSTATS
+ task->policy,
+ task->sched_info.cpu_time,
+ task->sched_info.run_delay,
+ task->sched_info.pcnt);
+#else
task->policy);
+#endif /* CONFIG_SCHEDSTATS */
if(mm)
mmput(mm);
return res;
diff -rupN linux-2.6.8.1/fs/proc/proc_misc.c linux-2.6.8.1-ss/fs/proc/proc_misc.c
--- linux-2.6.8.1/fs/proc/proc_misc.c 2004-08-14 03:54:50.000000000 -0700
+++ linux-2.6.8.1-ss/fs/proc/proc_misc.c 2004-09-07 22:30:10.000000000 -0700
@@ -282,6 +282,10 @@ static struct file_operations proc_vmsta
.release = seq_release,
};

+#ifdef CONFIG_SCHEDSTATS
+extern struct file_operations proc_schedstat_operations;
+#endif
+
#ifdef CONFIG_PROC_HARDWARE
static int hardware_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
@@ -681,6 +685,9 @@ void __init proc_misc_init(void)
#ifdef CONFIG_MODULES
create_seq_entry("modules", 0, &proc_modules_operations);
#endif
+#ifdef CONFIG_SCHEDSTATS
+ create_seq_entry("schedstat", 0, &proc_schedstat_operations);
+#endif
#ifdef CONFIG_PROC_KCORE
proc_root_kcore = create_proc_entry("kcore", S_IRUSR, NULL);
if (proc_root_kcore) {
diff -rupN linux-2.6.8.1/include/linux/sched.h linux-2.6.8.1-ss/include/linux/sched.h
--- linux-2.6.8.1/include/linux/sched.h 2004-08-14 03:54:49.000000000 -0700
+++ linux-2.6.8.1-ss/include/linux/sched.h 2004-09-07 22:53:00.000000000 -0700
@@ -96,6 +96,16 @@ extern unsigned long nr_running(void);
extern unsigned long nr_uninterruptible(void);
extern unsigned long nr_iowait(void);

+#ifdef CONFIG_SCHEDSTATS
+struct sched_info;
+extern void cpu_sched_info(struct sched_info *, int);
+#define schedstat_inc(rq, field) rq->field++;
+#define schedstat_add(rq, field, amt) rq->field += amt;
+#else
+#define schedstat_inc(rq, field) do { } while (0);
+#define schedstat_add(rq, field, amt) do { } while (0);
+#endif
+
#include <linux/time.h>
#include <linux/param.h>
#include <linux/resource.h>
@@ -347,6 +357,18 @@ struct k_itimer {
struct timespec wall_to_prev; /* wall_to_monotonic used when set */
};

+#ifdef CONFIG_SCHEDSTATS
+struct sched_info {
+ /* cumulative counters */
+ unsigned long cpu_time, /* time spent on the cpu */
+ run_delay, /* time spent waiting on a runqueue */
+ pcnt; /* # of timeslices run on this cpu */
+
+ /* timestamps */
+ unsigned long last_arrival, /* when we last ran on a cpu */
+ last_queued; /* when we were last queued to run */
+};
+#endif /* CONFIG_SCHEDSTATS */

struct io_context; /* See blkdev.h */
void exit_io_context(void);
@@ -409,6 +431,10 @@ struct task_struct {
cpumask_t cpus_allowed;
unsigned int time_slice, first_time_slice;

+#ifdef CONFIG_SCHEDSTATS
+ struct sched_info sched_info;
+#endif /* CONFIG_SCHEDSTATS */
+
struct list_head tasks;
/*
* ptrace_list/ptrace_children forms the list of my children
@@ -564,6 +590,14 @@ do { if (atomic_dec_and_test(&(tsk)->usa
#define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */
#define PF_SYNCWRITE 0x00200000 /* I am doing a sync write */

+enum idle_type
+{
+ IDLE,
+ NOT_IDLE,
+ NEWLY_IDLE,
+ MAX_IDLE_TYPES
+};
+
#ifdef CONFIG_SMP
#define SCHED_LOAD_SCALE 128UL /* increase resolution of load */

@@ -606,6 +640,23 @@ struct sched_domain {
unsigned long last_balance; /* init to jiffies. units in jiffies */
unsigned int balance_interval; /* initialise to 1. units in ms. */
unsigned int nr_balance_failed; /* initialise to 0 */
+
+#ifdef CONFIG_SCHEDSTATS
+ /* load_balance() stats */
+ unsigned long lb_cnt[MAX_IDLE_TYPES];
+ unsigned long lb_failed[MAX_IDLE_TYPES];
+ unsigned long lb_imbalance[MAX_IDLE_TYPES];
+ unsigned long lb_nobusyg[MAX_IDLE_TYPES];
+ unsigned long lb_nobusyq[MAX_IDLE_TYPES];
+
+ /* sched_balance_exec() stats */
+ unsigned long sbe_attempts;
+ unsigned long sbe_pushed;
+
+ /* try_to_wake_up() stats */
+ unsigned long ttwu_wake_affine;
+ unsigned long ttwu_wake_balance;
+#endif
};

/* Common values for SMT siblings */
diff -rupN linux-2.6.8.1/kernel/fork.c linux-2.6.8.1-ss/kernel/fork.c
--- linux-2.6.8.1/kernel/fork.c 2004-08-14 03:54:49.000000000 -0700
+++ linux-2.6.8.1-ss/kernel/fork.c 2004-09-07 22:30:10.000000000 -0700
@@ -965,6 +965,11 @@ struct task_struct *copy_process(unsigne
p->security = NULL;
p->io_context = NULL;
p->audit_context = NULL;
+
+#ifdef CONFIG_SCHEDSTATS
+ memset(&p->sched_info, 0, sizeof(p->sched_info));
+#endif /* CONFIG_SCHEDSTATS */
+
#ifdef CONFIG_NUMA
p->mempolicy = mpol_copy(p->mempolicy);
if (IS_ERR(p->mempolicy)) {
diff -rupN linux-2.6.8.1/kernel/sched.c linux-2.6.8.1-ss/kernel/sched.c
--- linux-2.6.8.1/kernel/sched.c 2004-08-14 03:55:59.000000000 -0700
+++ linux-2.6.8.1-ss/kernel/sched.c 2004-09-07 23:55:54.000000000 -0700
@@ -40,6 +40,8 @@
#include <linux/cpu.h>
#include <linux/percpu.h>
#include <linux/kthread.h>
+#include <linux/seq_file.h>
+#include <linux/times.h>
#include <asm/tlb.h>

#include <asm/unistd.h>
@@ -218,6 +220,9 @@ struct runqueue {
unsigned long expired_timestamp, nr_uninterruptible;
unsigned long long timestamp_last_tick;
task_t *curr, *idle;
+#ifdef CONFIG_SCHEDSTATS
+ int cpu; /* to make easy reverse-lookups with per-cpu runqueues */
+#endif
struct mm_struct *prev_mm;
prio_array_t *active, *expired, arrays[2];
int best_expired_prio;
@@ -233,6 +238,48 @@ struct runqueue {
task_t *migration_thread;
struct list_head migration_queue;
#endif
+
+#ifdef CONFIG_SCHEDSTATS
+ /* latency stats */
+ struct sched_info rq_sched_info;
+
+ /* sys_sched_yield() stats */
+ unsigned long yld_exp_empty;
+ unsigned long yld_act_empty;
+ unsigned long yld_both_empty;
+ unsigned long yld_cnt;
+
+ /* schedule() stats */
+ unsigned long sched_noswitch;
+ unsigned long sched_switch;
+ unsigned long sched_cnt;
+ unsigned long sched_goidle;
+
+ /* pull_task() stats */
+ unsigned long pt_gained[MAX_IDLE_TYPES];
+ unsigned long pt_lost[MAX_IDLE_TYPES];
+
+ /* active_load_balance() stats */
+ unsigned long alb_cnt;
+ unsigned long alb_lost;
+ unsigned long alb_gained;
+ unsigned long alb_failed;
+
+ /* try_to_wake_up() stats */
+ unsigned long ttwu_cnt;
+ unsigned long ttwu_attempts;
+ unsigned long ttwu_moved;
+
+ /* wake_up_forked_thread() stats */
+ unsigned long wuft_cnt;
+ unsigned long wuft_moved;
+
+ /* sched_migrate_task() stats */
+ unsigned long smt_cnt;
+
+ /* sched_balance_exec() stats */
+ unsigned long sbe_cnt;
+#endif
};

static DEFINE_PER_CPU(struct runqueue, runqueues);
@@ -279,6 +326,100 @@ static inline void task_rq_unlock(runque
spin_unlock_irqrestore(&rq->lock, *flags);
}

+#ifdef CONFIG_SCHEDSTATS
+/*
+ * bump this up when changing the output format or the meaning of an existing
+ * format, so that tools can adapt (or abort)
+ */
+#define SCHEDSTAT_VERSION 9
+
+static int show_schedstat(struct seq_file *seq, void *v)
+{
+ int cpu;
+ enum idle_type itype;
+
+ seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
+ seq_printf(seq, "timestamp %lu\n", jiffies);
+ for_each_online_cpu (cpu) {
+
+ runqueue_t *rq = cpu_rq(cpu);
+#ifdef CONFIG_SMP
+ struct sched_domain *sd;
+ int dcnt = 0;
+#endif
+
+ /* runqueue-specific stats */
+ seq_printf(seq,
+ "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu "
+ "%lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
+ cpu, rq->yld_both_empty,
+ rq->yld_act_empty, rq->yld_exp_empty,
+ rq->yld_cnt, rq->sched_noswitch,
+ rq->sched_switch, rq->sched_cnt, rq->sched_goidle,
+ rq->alb_cnt, rq->alb_gained, rq->alb_lost,
+ rq->alb_failed,
+ rq->ttwu_cnt, rq->ttwu_moved, rq->ttwu_attempts,
+ rq->wuft_cnt, rq->wuft_moved,
+ rq->smt_cnt, rq->sbe_cnt, rq->rq_sched_info.cpu_time,
+ rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt);
+
+ for (itype = IDLE; itype < MAX_IDLE_TYPES; itype++)
+ seq_printf(seq, " %lu %lu", rq->pt_gained[itype],
+ rq->pt_lost[itype]);
+
+ seq_printf(seq, "\n");
+
+#ifdef CONFIG_SMP
+ /* domain-specific stats */
+ for_each_domain(cpu, sd) {
+ char mask_str[NR_CPUS];
+
+ cpumask_scnprintf(mask_str, NR_CPUS, sd->span);
+ seq_printf(seq, "domain%d %s", dcnt++, mask_str);
+ for (itype = IDLE; itype < MAX_IDLE_TYPES; itype++) {
+ seq_printf(seq, " %lu %lu %lu %lu %lu",
+ sd->lb_cnt[itype],
+ sd->lb_failed[itype],
+ sd->lb_imbalance[itype],
+ sd->lb_nobusyq[itype],
+ sd->lb_nobusyg[itype]);
+ }
+ seq_printf(seq, " %lu %lu %lu %lu\n",
+ sd->sbe_pushed, sd->sbe_attempts,
+ sd->ttwu_wake_affine, sd->ttwu_wake_balance);
+ }
+#endif
+ }
+ return 0;
+}
+
+static int schedstat_open(struct inode *inode, struct file *file)
+{
+ unsigned size = PAGE_SIZE * (1 + num_online_cpus() / 32);
+ char *buf = kmalloc(size, GFP_KERNEL);
+ struct seq_file *m;
+ int res;
+
+ if (!buf)
+ return -ENOMEM;
+ res = single_open(file, show_schedstat, NULL);
+ if (!res) {
+ m = file->private_data;
+ m->buf = buf;
+ m->size = size;
+ } else
+ kfree(buf);
+ return res;
+}
+
+struct file_operations proc_schedstat_operations = {
+ .open = schedstat_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+#endif
+
/*
* rq_lock - lock a given runqueue and disable interrupts.
*/
@@ -298,6 +439,113 @@ static inline void rq_unlock(runqueue_t
spin_unlock_irq(&rq->lock);
}

+#ifdef CONFIG_SCHEDSTATS
+/*
+ * Called when a process is dequeued from the active array and given
+ * the cpu. We should note that with the exception of interactive
+ * tasks, the expired queue will become the active queue after the active
+ * queue is empty, without explicitly dequeuing and requeuing tasks in the
+ * expired queue. (Interactive tasks may be requeued directly to the
+ * active queue, thus delaying tasks in the expired queue from running;
+ * see scheduler_tick()).
+ *
+ * This function is only called from sched_info_arrive(), rather than
+ * dequeue_task(). Even though a task may be queued and dequeued multiple
+ * times as it is shuffled about, we're really interested in knowing how
+ * long it was from the *first* time it was queued to the time that it
+ * finally hit a cpu.
+ */
+static inline void sched_info_dequeued(task_t *t)
+{
+ t->sched_info.last_queued = 0;
+}
+
+/*
+ * Called when a task finally hits the cpu. We can now calculate how
+ * long it was waiting to run. We also note when it began so that we
+ * can keep stats on how long its timeslice is.
+ */
+static inline void sched_info_arrive(task_t *t)
+{
+ unsigned long now = jiffies;
+ unsigned long diff = 0;
+ struct runqueue *rq = task_rq(t);
+
+ if (t->sched_info.last_queued)
+ diff = now - t->sched_info.last_queued;
+ sched_info_dequeued(t);
+ t->sched_info.run_delay += diff;
+ t->sched_info.last_arrival = now;
+ t->sched_info.pcnt++;
+
+ if (!rq)
+ return;
+
+ rq->rq_sched_info.run_delay += diff;
+ rq->rq_sched_info.pcnt++;
+}
+
+/*
+ * Called when a process is queued into either the active or expired
+ * array. The time is noted and later used to determine how long we
+ * had to wait for us to reach the cpu. Since the expired queue will
+ * become the active queue after active queue is empty, without dequeuing
+ * and requeuing any tasks, we are interested in queuing to either. It
+ * is unusual but not impossible for tasks to be dequeued and immediately
+ * requeued in the same or another array: this can happen in sched_yield(),
+ * set_user_nice(), and even load_balance() as it moves tasks from runqueue
+ * to runqueue.
+ *
+ * This function is only called from enqueue_task(), but also only updates
+ * the timestamp if it is already not set. It's assumed that
+ * sched_info_dequeued() will clear that stamp when appropriate.
+ */
+static inline void sched_info_queued(task_t *t)
+{
+ if (!t->sched_info.last_queued)
+ t->sched_info.last_queued = jiffies;
+}
+
+/*
+ * Called when a process ceases being the active-running process, either
+ * voluntarily or involuntarily. Now we can calculate how long we ran.
+ */
+static inline void sched_info_depart(task_t *t)
+{
+ struct runqueue *rq = task_rq(t);
+ unsigned long diff = jiffies - t->sched_info.last_arrival;
+
+ t->sched_info.cpu_time += diff;
+
+ if (rq)
+ rq->rq_sched_info.cpu_time += diff;
+}
+
+/*
+ * Called when tasks are switched involuntarily due, typically, to expiring
+ * their time slice. (This may also be called when switching to or from
+ * the idle task.) We are only called when prev != next.
+ */
+static inline void sched_info_switch(task_t *prev, task_t *next)
+{
+ struct runqueue *rq = task_rq(prev);
+
+ /*
+ * prev now departs the cpu. It's not interesting to record
+ * stats about how efficient we were at scheduling the idle
+ * process, however.
+ */
+ if (prev != rq->idle)
+ sched_info_depart(prev);
+
+ if (next != rq->idle)
+ sched_info_arrive(next);
+}
+#else
+#define sched_info_queued(t) {}
+#define sched_info_switch(t, next) {}
+#endif /* CONFIG_SCHEDSTATS */
+
/*
* Adding/removing a task to/from a priority array:
*/
@@ -311,6 +559,7 @@ static void dequeue_task(struct task_str

static void enqueue_task(struct task_struct *p, prio_array_t *array)
{
+ sched_info_queued(p);
list_add_tail(&p->run_list, array->queue + p->prio);
__set_bit(p->prio, array->bitmap);
array->nr_active++;
@@ -735,11 +984,12 @@ static int try_to_wake_up(task_t * p, un
runqueue_t *rq;
#ifdef CONFIG_SMP
unsigned long load, this_load;
- struct sched_domain *sd;
+ struct sched_domain *sd = NULL;
int new_cpu;
#endif

rq = task_rq_lock(p, &flags);
+ schedstat_inc(rq, ttwu_cnt);
old_state = p->state;
if (!(old_state & state))
goto out;
@@ -787,23 +1037,35 @@ static int try_to_wake_up(task_t * p, un
*/
imbalance = sd->imbalance_pct + (sd->imbalance_pct - 100) / 2;

- if ( ((sd->flags & SD_WAKE_AFFINE) &&
- !task_hot(p, rq->timestamp_last_tick, sd))
- || ((sd->flags & SD_WAKE_BALANCE) &&
- imbalance*this_load <= 100*load) ) {
+ if ((sd->flags & SD_WAKE_AFFINE) &&
+ !task_hot(p, rq->timestamp_last_tick, sd)) {
+ /*
+ * This domain has SD_WAKE_AFFINE and p is cache cold
+ * in this domain.
+ */
+ if (cpu_isset(cpu, sd->span)) {
+ schedstat_inc(sd, ttwu_wake_affine);
+ goto out_set_cpu;
+ }
+ } else if ((sd->flags & SD_WAKE_BALANCE) &&
+ imbalance*this_load <= 100*load) {
/*
- * Now sd has SD_WAKE_AFFINE and p is cache cold in sd
- * or sd has SD_WAKE_BALANCE and there is an imbalance
+ * This domain has SD_WAKE_BALANCE and there is
+ * an imbalance.
*/
- if (cpu_isset(cpu, sd->span))
+ if (cpu_isset(cpu, sd->span)) {
+ schedstat_inc(sd, ttwu_wake_balance);
goto out_set_cpu;
+ }
}
}

new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
out_set_cpu:
+ schedstat_inc(rq, ttwu_attempts);
new_cpu = wake_idle(new_cpu, p);
if (new_cpu != cpu && cpu_isset(new_cpu, p->cpus_allowed)) {
+ schedstat_inc(rq, ttwu_moved);
set_task_cpu(p, new_cpu);
task_rq_unlock(rq, &flags);
/* might preempt at this point */
@@ -855,7 +1117,7 @@ out:
int fastcall wake_up_process(task_t * p)
{
return try_to_wake_up(p, TASK_STOPPED |
- TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
+ TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
}

EXPORT_SYMBOL(wake_up_process);
@@ -1155,13 +1417,6 @@ static void double_rq_unlock(runqueue_t
spin_unlock(&rq2->lock);
}

-enum idle_type
-{
- IDLE,
- NOT_IDLE,
- NEWLY_IDLE,
-};
-
#ifdef CONFIG_SMP

/*
@@ -1228,6 +1483,7 @@ void fastcall wake_up_forked_thread(task
* Find the largest domain that this CPU is part of that
* is willing to balance on clone:
*/
+ schedstat_inc(this_rq, wuft_cnt);
for_each_domain(this_cpu, tmp)
if (tmp->flags & SD_BALANCE_CLONE)
sd = tmp;
@@ -1280,6 +1536,7 @@ lock_again:
rq->nr_running++;
}
} else {
+ schedstat_inc(this_rq, wuft_moved);
/* Not the local CPU - must adjust timestamp */
p->timestamp = (p->timestamp - this_rq->timestamp_last_tick)
+ rq->timestamp_last_tick;
@@ -1310,6 +1567,7 @@ static void sched_migrate_task(task_t *p
|| unlikely(cpu_is_offline(dest_cpu)))
goto out;

+ schedstat_inc(rq, smt_cnt);
/* force the process onto the specified CPU */
if (migrate_task(p, dest_cpu, &req)) {
/* Need to wait for migration thread (might exit: take ref). */
@@ -1337,6 +1595,7 @@ void sched_balance_exec(void)
struct sched_domain *tmp, *sd = NULL;
int new_cpu, this_cpu = get_cpu();

+ schedstat_inc(this_rq(), sbe_cnt);
/* Prefer the current CPU if there's only this task running */
if (this_rq()->nr_running <= 1)
goto out;
@@ -1345,9 +1604,11 @@ void sched_balance_exec(void)
if (tmp->flags & SD_BALANCE_EXEC)
sd = tmp;

+ schedstat_inc(sd, sbe_attempts);
if (sd) {
new_cpu = find_idlest_cpu(current, this_cpu, sd);
if (new_cpu != this_cpu) {
+ schedstat_inc(sd, sbe_pushed);
put_cpu();
sched_migrate_task(current, new_cpu);
return;
@@ -1486,6 +1747,15 @@ skip_queue:
idx++;
goto skip_bitmap;
}
+
+ /*
+ * Right now, this is the only place pull_task() is called,
+ * so we can safely collect pull_task() stats here rather than
+ * inside pull_task().
+ */
+ schedstat_inc(this_rq, pt_gained[idle]);
+ schedstat_inc(busiest, pt_lost[idle]);
+
pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
pulled++;

@@ -1680,14 +1950,20 @@ static int load_balance(int this_cpu, ru
int nr_moved;

spin_lock(&this_rq->lock);
-
- group = find_busiest_group(sd, this_cpu, &imbalance, idle);
- if (!group)
- goto out_balanced;
+ schedstat_inc(sd, lb_cnt[idle]);
+
+ group = find_busiest_group(sd, this_cpu, &imbalance, idle);
+ if (!group) {
+ schedstat_inc(sd, lb_nobusyg[idle]);
+ goto out_balanced;
+ }

busiest = find_busiest_queue(group);
- if (!busiest)
- goto out_balanced;
+ if (!busiest) {
+ schedstat_inc(sd, lb_nobusyq[idle]);
+ goto out_balanced;
+ }
+
/*
* This should be "impossible", but since load
* balancing is inherently racy and statistical,
@@ -1698,6 +1974,8 @@ static int load_balance(int this_cpu, ru
goto out_balanced;
}

+ schedstat_add(sd, lb_imbalance[idle], imbalance);
+
nr_moved = 0;
if (busiest->nr_running > 1) {
/*
@@ -1714,6 +1992,7 @@ static int load_balance(int this_cpu, ru
spin_unlock(&this_rq->lock);

if (!nr_moved) {
+ schedstat_inc(sd, lb_failed[idle]);
sd->nr_balance_failed++;

if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
@@ -1768,20 +2047,29 @@ static int load_balance_newidle(int this
unsigned long imbalance;
int nr_moved = 0;

+ schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE);
- if (!group)
+ if (!group) {
+ schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);
goto out;
+ }

busiest = find_busiest_queue(group);
- if (!busiest || busiest == this_rq)
+ if (!busiest || busiest == this_rq) {
+ schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
goto out;
+ }

/* Attempt to move tasks */
double_lock_balance(this_rq, busiest);

+ schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
nr_moved = move_tasks(this_rq, this_cpu, busiest,
imbalance, sd, NEWLY_IDLE);

+ if (!nr_moved)
+ schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
+
spin_unlock(&busiest->lock);

out:
@@ -1820,6 +2108,7 @@ static void active_load_balance(runqueue
struct sched_group *group, *busy_group;
int i;

+ schedstat_inc(busiest, alb_cnt);
if (busiest->nr_running <= 1)
return;

@@ -1866,7 +2155,12 @@ static void active_load_balance(runqueue
if (unlikely(busiest == rq))
goto next_group;
double_lock_balance(busiest, rq);
- move_tasks(rq, push_cpu, busiest, 1, sd, IDLE);
+ if (move_tasks(rq, push_cpu, busiest, 1, sd, IDLE)) {
+ schedstat_inc(busiest, alb_lost);
+ schedstat_inc(rq, alb_gained);
+ } else {
+ schedstat_inc(busiest, alb_failed);
+ }
spin_unlock(&rq->lock);
next_group:
group = group->next;
@@ -2210,6 +2504,7 @@ need_resched:
rq = this_rq();

release_kernel_lock(prev);
+ schedstat_inc(rq, sched_cnt);
now = sched_clock();
if (likely(now - prev->timestamp < NS_MAX_SLEEP_AVG))
run_time = now - prev->timestamp;
@@ -2256,18 +2551,21 @@ need_resched:
/*
* Switch the active and expired arrays.
*/
+ schedstat_inc(rq, sched_switch);
rq->active = rq->expired;
rq->expired = array;
array = rq->active;
rq->expired_timestamp = 0;
rq->best_expired_prio = MAX_PRIO;
- }
+ } else
+ schedstat_inc(rq, sched_noswitch);

idx = sched_find_first_bit(array->bitmap);
queue = array->queue + idx;
next = list_entry(queue->next, task_t, run_list);

if (dependent_sleeper(cpu, rq, next)) {
+ schedstat_inc(rq, sched_goidle);
next = rq->idle;
goto switch_tasks;
}
@@ -2297,6 +2595,7 @@ switch_tasks:
}
prev->timestamp = now;

+ sched_info_switch(prev, next);
if (likely(prev != next)) {
next->timestamp = now;
rq->nr_switches++;
@@ -3008,6 +3307,7 @@ asmlinkage long sys_sched_yield(void)
prio_array_t *array = current->array;
prio_array_t *target = rq->expired;

+ schedstat_inc(rq, yld_cnt);
/*
* We implement yielding by moving the task into the expired
* queue.
@@ -3018,6 +3318,15 @@ asmlinkage long sys_sched_yield(void)
if (unlikely(rt_task(current)))
target = rq->active;

+ if (current->array->nr_active == 1) {
+ schedstat_inc(rq, yld_act_empty);
+ if (!rq->expired->nr_active) {
+ schedstat_inc(rq, yld_both_empty);
+ }
+ } else if (!rq->expired->nr_active) {
+ schedstat_inc(rq, yld_exp_empty);
+ }
+
dequeue_task(current, array);
enqueue_task(current, target);

@@ -3603,7 +3912,7 @@ static int migration_call(struct notifie
rq->idle->static_prio = MAX_PRIO;
__setscheduler(rq->idle, SCHED_NORMAL, 0);
task_rq_unlock(rq, &flags);
- BUG_ON(rq->nr_running != 0);
+ BUG_ON(rq->nr_running != 0);

/* No need to migrate the tasks: it was best-effort if
* they didn't do lock_cpu_hotplug(). Just wake up
@@ -3618,7 +3927,7 @@ static int migration_call(struct notifie
complete(&req->done);
}
spin_unlock_irq(&rq->lock);
- break;
+ break;
#endif
}
return NOTIFY_OK;
@@ -3937,6 +4246,9 @@ void __init sched_init(void)
spin_lock_init(&rq->lock);
rq->active = rq->arrays;
rq->expired = rq->arrays + 1;
+#ifdef CONFIG_SCHEDSTATS
+ rq->cpu = i;
+#endif /* CONFIG_SCHEDSTATS */
rq->best_expired_prio = MAX_PRIO;

#ifdef CONFIG_SMP