From: Chandra Seetharaman Make the task-related schedstats functions callable by delay accounting even if schedstats collection isn't turned on. This removes the dependency of delay accounting on schedstats. Signed-off-by: Chandra Seetharaman Signed-off-by: Shailabh Nagar Signed-off-by: Balbir Singh Cc: Jes Sorensen Cc: Peter Chubb Cc: Erich Focht Cc: Levent Serinol Cc: Jay Lan DESC Use better names in schedstats EDESC From: Balbir Singh On Mon, May 08, 2006 at 02:26:40PM -0700, Andrew Morton wrote: > Balbir Singh wrote: > > > > +/* > > + * Expects runqueue lock to be held for atomicity of update > > + */ > > +static inline void rq_sched_info_arrive(struct runqueue *rq, > > + unsigned long diff) > > +{ > > + if (rq) { > > + rq->rq_sched_info.run_delay += diff; > > + rq->rq_sched_info.pcnt++; > > + } > > +} > > + > > +/* > > + * Expects runqueue lock to be held for atomicity of update > > + */ > > +static inline void rq_sched_info_depart(struct runqueue *rq, > > + unsigned long diff) > > +{ > > + if (rq) > > + rq->rq_sched_info.cpu_time += diff; > > +} > > The kernel has many different units of time - jiffies, cpu ticks, ns, us, > ms, etc. So the reader of these functions doesn't have a clue what "diff" > is. > > A good way to remove all doubt in all cases is to include the units in the > variable's name. Something like delta_jiffies, perhaps. Hi, Andrew I have renamed all the "diff" to "delta_jiffies" to make it easier to read the code as suggested in the review comments. Balbir Singh, Linux Technology Center, IBM Software Labs Changelog 1. Clean up the usage of the names. Use names with units to make the code easier to read Signed-off-by: Balbir Singh Signed-off-by: Shailabh Nagar Cc: Jes Sorensen Cc: Peter Chubb Cc: Erich Focht Cc: Levent Serinol Cc: Jay Lan Signed-off-by: Andrew Morton --- include/linux/sched.h | 20 +++++++++-- kernel/sched.c | 71 +++++++++++++++++++++++++++------------- 2 files changed, 66 insertions(+), 25 deletions(-) diff -puN include/linux/sched.h~per-task-delay-accounting-cpu-delay-collection-via-schedstats include/linux/sched.h --- a/include/linux/sched.h~per-task-delay-accounting-cpu-delay-collection-via-schedstats +++ a/include/linux/sched.h @@ -537,7 +537,7 @@ extern struct user_struct root_user; struct backing_dev_info; struct reclaim_state; -#ifdef CONFIG_SCHEDSTATS +#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) struct sched_info { /* cumulative counters */ unsigned long cpu_time, /* time spent on the cpu */ @@ -548,9 +548,11 @@ struct sched_info { unsigned long last_arrival, /* when we last ran on a cpu */ last_queued; /* when we were last queued to run */ }; +#endif /* defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) */ +#ifdef CONFIG_SCHEDSTATS extern struct file_operations proc_schedstat_operations; -#endif +#endif /* CONFIG_SCHEDSTATS */ #ifdef CONFIG_TASK_DELAY_ACCT struct task_delay_info { @@ -580,7 +582,19 @@ struct task_delay_info { u32 swapin_count; /* total count of the number of swapin block */ /* io operations performed */ }; +#endif /* CONFIG_TASK_DELAY_ACCT */ + +static inline int sched_info_on(void) +{ +#ifdef CONFIG_SCHEDSTATS + return 1; +#elif defined(CONFIG_TASK_DELAY_ACCT) + extern int delayacct_on; + return delayacct_on; +#else + return 0; #endif +} enum idle_type { @@ -777,7 +791,7 @@ struct task_struct { cpumask_t cpus_allowed; unsigned int time_slice, first_time_slice; -#ifdef CONFIG_SCHEDSTATS +#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) struct sched_info sched_info; #endif diff -puN kernel/sched.c~per-task-delay-accounting-cpu-delay-collection-via-schedstats kernel/sched.c --- a/kernel/sched.c~per-task-delay-accounting-cpu-delay-collection-via-schedstats +++ a/kernel/sched.c @@ -502,9 +502,36 @@ struct file_operations proc_schedstat_op .release = single_release, }; +/* + * Expects runqueue lock to be held for atomicity of update + */ +static inline void +rq_sched_info_arrive(struct rq *rq, unsigned long delta_jiffies) +{ + if (rq) { + rq->rq_sched_info.run_delay += delta_jiffies; + rq->rq_sched_info.pcnt++; + } +} + +/* + * Expects runqueue lock to be held for atomicity of update + */ +static inline void +rq_sched_info_depart(struct rq *rq, unsigned long delta_jiffies) +{ + if (rq) + rq->rq_sched_info.cpu_time += delta_jiffies; +} # define schedstat_inc(rq, field) do { (rq)->field++; } while (0) # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0) #else /* !CONFIG_SCHEDSTATS */ +static inline void +rq_sched_info_arrive(struct rq *rq, unsigned long delta_jiffies) +{} +static inline void +rq_sched_info_depart(struct rq *rq, unsigned long delta_jiffies) +{} # define schedstat_inc(rq, field) do { } while (0) # define schedstat_add(rq, field, amt) do { } while (0) #endif @@ -524,7 +551,7 @@ static inline struct rq *this_rq_lock(vo return rq; } -#ifdef CONFIG_SCHEDSTATS +#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) /* * Called when a process is dequeued from the active array and given * the cpu. We should note that with the exception of interactive @@ -552,21 +579,16 @@ static inline void sched_info_dequeued(s */ static void sched_info_arrive(struct task_struct *t) { - unsigned long now = jiffies, diff = 0; - struct rq *rq = task_rq(t); + unsigned long now = jiffies, delta_jiffies = 0; if (t->sched_info.last_queued) - diff = now - t->sched_info.last_queued; + delta_jiffies = now - t->sched_info.last_queued; sched_info_dequeued(t); - t->sched_info.run_delay += diff; + t->sched_info.run_delay += delta_jiffies; 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++; + rq_sched_info_arrive(task_rq(t), delta_jiffies); } /* @@ -586,8 +608,9 @@ static void sched_info_arrive(struct tas */ static inline void sched_info_queued(struct task_struct *t) { - if (!t->sched_info.last_queued) - t->sched_info.last_queued = jiffies; + if (unlikely(sched_info_on())) + if (!t->sched_info.last_queued) + t->sched_info.last_queued = jiffies; } /* @@ -596,13 +619,10 @@ static inline void sched_info_queued(str */ static inline void sched_info_depart(struct task_struct *t) { - struct rq *rq = task_rq(t); - unsigned long diff = jiffies - t->sched_info.last_arrival; - - t->sched_info.cpu_time += diff; + unsigned long delta_jiffies = jiffies - t->sched_info.last_arrival; - if (rq) - rq->rq_sched_info.cpu_time += diff; + t->sched_info.cpu_time += delta_jiffies; + rq_sched_info_depart(task_rq(t), delta_jiffies); } /* @@ -611,7 +631,7 @@ static inline void sched_info_depart(str * the idle task.) We are only called when prev != next. */ static inline void -sched_info_switch(struct task_struct *prev, struct task_struct *next) +__sched_info_switch(struct task_struct *prev, struct task_struct *next) { struct rq *rq = task_rq(prev); @@ -626,10 +646,16 @@ sched_info_switch(struct task_struct *pr if (next != rq->idle) sched_info_arrive(next); } +static inline void +sched_info_switch(struct task_struct *prev, struct task_struct *next) +{ + if (unlikely(sched_info_on())) + __sched_info_switch(prev, next); +} #else #define sched_info_queued(t) do { } while (0) #define sched_info_switch(t, next) do { } while (0) -#endif /* CONFIG_SCHEDSTATS */ +#endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */ /* * Adding/removing a task to/from a priority array: @@ -1531,8 +1557,9 @@ void fastcall sched_fork(struct task_str INIT_LIST_HEAD(&p->run_list); p->array = NULL; -#ifdef CONFIG_SCHEDSTATS - memset(&p->sched_info, 0, sizeof(p->sched_info)); +#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) + if (unlikely(sched_info_on())) + memset(&p->sched_info, 0, sizeof(p->sched_info)); #endif #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) p->oncpu = 0; _