From: Rick Lindsley Contributions from various people, including Nick and Ingo. It adds lots of CPU scheduler stats in /proc/pid/stat. They are described in the new Documentation//sched-stats.txt We were carrying this patch offline for some time, but as there's still considerable ongoing work in this area, and as the new stats are a configuration option, I think it's best that this capability be in the base kernel. Signed-off-by: Andrew Morton --- 25-akpm/Documentation/sched-stats.txt | 150 ++++++++++++++ 25-akpm/arch/i386/Kconfig | 13 + 25-akpm/arch/ppc/Kconfig | 13 + 25-akpm/arch/ppc64/Kconfig | 13 + 25-akpm/arch/x86_64/Kconfig | 13 + 25-akpm/fs/proc/array.c | 13 + 25-akpm/fs/proc/proc_misc.c | 7 25-akpm/include/linux/sched.h | 51 ++++ 25-akpm/kernel/fork.c | 5 25-akpm/kernel/sched.c | 355 +++++++++++++++++++++++++++++++--- 10 files changed, 606 insertions(+), 27 deletions(-) diff -puN arch/i386/Kconfig~schedstats-2 arch/i386/Kconfig --- 25/arch/i386/Kconfig~schedstats-2 2004-08-04 23:53:24.746375576 -0700 +++ 25-akpm/arch/i386/Kconfig 2004-08-04 23:53:24.765372688 -0700 @@ -1482,6 +1482,19 @@ 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 -puN arch/ppc64/Kconfig~schedstats-2 arch/ppc64/Kconfig --- 25/arch/ppc64/Kconfig~schedstats-2 2004-08-04 23:53:24.748375272 -0700 +++ 25-akpm/arch/ppc64/Kconfig 2004-08-04 23:53:24.766372536 -0700 @@ -434,6 +434,19 @@ config SPINLINE If in doubt, 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. + endmenu source "security/Kconfig" diff -puN arch/ppc/Kconfig~schedstats-2 arch/ppc/Kconfig --- 25/arch/ppc/Kconfig~schedstats-2 2004-08-04 23:53:24.750374968 -0700 +++ 25-akpm/arch/ppc/Kconfig 2004-08-04 23:53:24.768372232 -0700 @@ -1368,6 +1368,19 @@ 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 -puN arch/x86_64/Kconfig~schedstats-2 arch/x86_64/Kconfig --- 25/arch/x86_64/Kconfig~schedstats-2 2004-08-04 23:53:24.751374816 -0700 +++ 25-akpm/arch/x86_64/Kconfig 2004-08-04 23:53:24.769372080 -0700 @@ -464,6 +464,19 @@ 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 -puN /dev/null Documentation/sched-stats.txt --- /dev/null 2003-09-15 06:40:47.000000000 -0700 +++ 25-akpm/Documentation/sched-stats.txt 2004-08-04 23:53:24.770371928 -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 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 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//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//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 -puN fs/proc/array.c~schedstats-2 fs/proc/array.c --- 25/fs/proc/array.c~schedstats-2 2004-08-04 23:53:24.753374512 -0700 +++ 25-akpm/fs/proc/array.c 2004-08-04 23:53:24.771371776 -0700 @@ -357,9 +357,15 @@ 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, @@ -404,7 +410,14 @@ 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 -puN fs/proc/proc_misc.c~schedstats-2 fs/proc/proc_misc.c --- 25/fs/proc/proc_misc.c~schedstats-2 2004-08-04 23:53:24.755374208 -0700 +++ 25-akpm/fs/proc/proc_misc.c 2004-08-04 23:53:24.772371624 -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) @@ -711,6 +715,9 @@ 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 -puN include/linux/sched.h~schedstats-2 include/linux/sched.h --- 25/include/linux/sched.h~schedstats-2 2004-08-04 23:53:24.757373904 -0700 +++ 25-akpm/include/linux/sched.h 2004-08-04 23:53:24.774371320 -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 #include #include @@ -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 @@ -574,6 +600,14 @@ do { if (atomic_dec_and_test(&(tsk)->usa #define SD_WAKE_BALANCE 16 /* Perform balancing at task wakeup */ #define SD_SHARE_CPUPOWER 32 /* Domain members share cpu power */ +enum idle_type +{ + IDLE, + NOT_IDLE, + NEWLY_IDLE, + MAX_IDLE_TYPES +}; + struct sched_group { struct sched_group *next; /* Must be a circular list */ cpumask_t cpumask; @@ -605,6 +639,23 @@ 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 }; #ifndef ARCH_HAS_SCHED_TUNE diff -puN kernel/fork.c~schedstats-2 kernel/fork.c --- 25/kernel/fork.c~schedstats-2 2004-08-04 23:53:24.758373752 -0700 +++ 25-akpm/kernel/fork.c 2004-08-04 23:53:24.775371168 -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 -puN kernel/sched.c~schedstats-2 kernel/sched.c --- 25/kernel/sched.c~schedstats-2 2004-08-04 23:53:24.760373448 -0700 +++ 25-akpm/kernel/sched.c 2004-08-04 23:53:24.781370256 -0700 @@ -41,6 +41,8 @@ #include #include #include +#include +#include #include #include @@ -234,6 +236,48 @@ 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); @@ -280,6 +324,97 @@ 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) { + + int dcnt = 0; + + runqueue_t *rq = cpu_rq(cpu); + struct sched_domain *sd; + + /* 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"); + + /* 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); + } + } + 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. */ @@ -299,6 +434,113 @@ 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: */ @@ -312,6 +554,7 @@ 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++; @@ -736,11 +979,12 @@ 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; @@ -788,23 +1032,35 @@ 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)) { /* - * 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_AFFINE and p is cache cold + * in this domain. */ - if (cpu_isset(cpu, sd->span)) + 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) { + /* + * This domain has SD_WAKE_BALANCE and there is + * an imbalance. + */ + 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 */ @@ -856,7 +1112,7 @@ 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); @@ -1162,13 +1418,6 @@ unsigned long nr_iowait(void) return sum; } -enum idle_type -{ - IDLE, - NOT_IDLE, - NEWLY_IDLE, -}; - #ifdef CONFIG_SMP /* @@ -1283,6 +1532,7 @@ 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). */ @@ -1310,6 +1560,7 @@ void sched_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; @@ -1318,9 +1569,11 @@ void sched_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; @@ -1444,6 +1697,15 @@ 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++; @@ -1638,14 +1900,20 @@ static int load_balance(int this_cpu, ru int nr_moved; spin_lock(&this_rq->lock); + schedstat_inc(sd, lb_cnt[idle]); - group = find_busiest_group(sd, this_cpu, &imbalance, idle); - if (!group) - goto out_balanced; + 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, @@ -1656,6 +1924,8 @@ 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) { /* @@ -1672,6 +1942,7 @@ 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)) { @@ -1726,20 +1997,29 @@ 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: @@ -1778,6 +2058,7 @@ 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; @@ -1824,7 +2105,12 @@ 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; @@ -2177,6 +2463,7 @@ need_resched: } 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; @@ -2223,18 +2510,21 @@ 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; } @@ -2264,6 +2554,7 @@ switch_tasks: } prev->timestamp = now; + sched_info_switch(prev, next); if (likely(prev != next)) { next->timestamp = now; rq->nr_switches++; @@ -2982,6 +3273,7 @@ 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. @@ -2992,6 +3284,15 @@ asmlinkage long sys_sched_yield(void) if (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); @@ -3578,7 +3879,7 @@ 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 @@ -3593,7 +3894,7 @@ static int migration_call(struct notifie complete(&req->done); } spin_unlock_irq(&rq->lock); - break; + break; #endif } return NOTIFY_OK; _