| Message ID | 1391728237-4441-4-git-send-email-daniel.lezcano@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 02/10/2014 11:04 AM, Preeti Murthy wrote: > Hi Daniel, > > On Fri, Feb 7, 2014 at 4:40 AM, Daniel Lezcano > <daniel.lezcano@linaro.org> wrote: >> The idle_balance modifies the idle_stamp field of the rq, making this >> information to be shared across core.c and fair.c. As we can know if the >> cpu is going to idle or not with the previous patch, let's encapsulate the >> idle_stamp information in core.c by moving it up to the caller. The >> idle_balance function returns true in case a balancing occured and the cpu >> won't be idle, false if no balance happened and the cpu is going idle. >> >> Cc: mingo@kernel.org >> Cc: alex.shi@linaro.org >> Cc: peterz@infradead.org >> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> >> Signed-off-by: Peter Zijlstra <peterz@infradead.org> >> --- >> kernel/sched/core.c | 13 +++++++++++-- >> kernel/sched/fair.c | 14 ++++++-------- >> kernel/sched/sched.h | 8 +------- >> 3 files changed, 18 insertions(+), 17 deletions(-) >> >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index 16b97dd..428ee4c 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -2704,8 +2704,17 @@ need_resched: >> >> pre_schedule(rq, prev); >> >> - if (unlikely(!rq->nr_running)) >> - idle_balance(rq); >> +#ifdef CONFIG_SMP >> + if (unlikely(!rq->nr_running)) { >> + /* >> + * We must set idle_stamp _before_ calling idle_balance(), such >> + * that we measure the duration of idle_balance() as idle time. > > Should not this be "such that we *do not* measure the duration of idle_balance() > as idle time?" Actually, the initial code was including the idle balance time processing in the idle stamp. When I moved the idle stamp in core.c, idle balance was no longer measured (an unwanted change). That has been fixed and to prevent that to occur again, we added a comment.
On 02/07/2014 07:10 AM, Daniel Lezcano wrote: > The idle_balance modifies the idle_stamp field of the rq, making this > information to be shared across core.c and fair.c. As we can know if the > cpu is going to idle or not with the previous patch, let's encapsulate the > idle_stamp information in core.c by moving it up to the caller. The > idle_balance function returns true in case a balancing occured and the cpu > won't be idle, false if no balance happened and the cpu is going idle. > > Cc: mingo@kernel.org > Cc: alex.shi@linaro.org > Cc: peterz@infradead.org > Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> > Signed-off-by: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Alex Shi <alex.shi@linaro.org>
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 16b97dd..428ee4c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2704,8 +2704,17 @@ need_resched: pre_schedule(rq, prev); - if (unlikely(!rq->nr_running)) - idle_balance(rq); +#ifdef CONFIG_SMP + if (unlikely(!rq->nr_running)) { + /* + * We must set idle_stamp _before_ calling idle_balance(), such + * that we measure the duration of idle_balance() as idle time. + */ + rq->idle_stamp = rq_clock(rq); + if (idle_balance(rq)) + rq->idle_stamp = 0; + } +#endif put_prev_task(rq, prev); next = pick_next_task(rq); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 5ebc681..04fea77 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6531,7 +6531,7 @@ out: * idle_balance is called by schedule() if this_cpu is about to become * idle. Attempts to pull tasks from other CPUs. */ -void idle_balance(struct rq *this_rq) +int idle_balance(struct rq *this_rq) { struct sched_domain *sd; int pulled_task = 0; @@ -6539,10 +6539,8 @@ void idle_balance(struct rq *this_rq) u64 curr_cost = 0; int this_cpu = this_rq->cpu; - this_rq->idle_stamp = rq_clock(this_rq); - if (this_rq->avg_idle < sysctl_sched_migration_cost) - return; + return 0; /* * Drop the rq->lock, but keep IRQ/preempt disabled. @@ -6580,10 +6578,8 @@ void idle_balance(struct rq *this_rq) interval = msecs_to_jiffies(sd->balance_interval); if (time_after(next_balance, sd->last_balance + interval)) next_balance = sd->last_balance + interval; - if (pulled_task) { - this_rq->idle_stamp = 0; + if (pulled_task) break; - } } rcu_read_unlock(); @@ -6594,7 +6590,7 @@ void idle_balance(struct rq *this_rq) * A task could have be enqueued in the meantime */ if (this_rq->nr_running && !pulled_task) - return; + return 1; if (pulled_task || time_after(jiffies, this_rq->next_balance)) { /* @@ -6606,6 +6602,8 @@ void idle_balance(struct rq *this_rq) if (curr_cost > this_rq->max_idle_balance_cost) this_rq->max_idle_balance_cost = curr_cost; + + return pulled_task; } /* diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 1436219..c08c070 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1176,17 +1176,11 @@ extern const struct sched_class idle_sched_class; extern void update_group_power(struct sched_domain *sd, int cpu); extern void trigger_load_balance(struct rq *rq); -extern void idle_balance(struct rq *this_rq); +extern int idle_balance(struct rq *this_rq); extern void idle_enter_fair(struct rq *this_rq); extern void idle_exit_fair(struct rq *this_rq); -#else /* CONFIG_SMP */ - -static inline void idle_balance(struct rq *rq) -{ -} - #endif extern void sysrq_sched_debug_show(void);