diff options
| author | Pavankumar Kondeti <pkondeti@codeaurora.org> | 2017-06-28 12:00:31 +0530 |
|---|---|---|
| committer | Pavankumar Kondeti <pkondeti@codeaurora.org> | 2017-08-07 16:08:23 +0530 |
| commit | a66b3eb5aff1536bc32e5e5eb60393610a21dd06 (patch) | |
| tree | 863007cd12e7f421e6854355d0ffd8b244deadf5 | |
| parent | ca652b3d74c674ee4847ce56199889fd247106e6 (diff) | |
softirq: defer softirq processing to ksoftirqd if CPU is busy with RT
Defer the softirq processing to ksoftirqd if a RT task is running
or queued on the current CPU. This complements the RT task placement
algorithm which tries to find a CPU that is not currently busy with
softirqs.
Currently NET_TX, NET_RX, BLOCK and TASKLET softirqs are only deferred
as they can potentially run for long time.
Change-Id: Id7665244af6bbd5a96d9e591cf26154e9eaa860c
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
| -rw-r--r-- | include/linux/sched.h | 5 | ||||
| -rw-r--r-- | kernel/sched/cpupri.c | 11 | ||||
| -rw-r--r-- | kernel/softirq.c | 5 |
3 files changed, 20 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 57042d91ae9c..baf107821d9a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2481,6 +2481,7 @@ extern void do_set_cpus_allowed(struct task_struct *p, extern int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask); +extern bool cpupri_check_rt(void); #else static inline void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) @@ -2493,6 +2494,10 @@ static inline int set_cpus_allowed_ptr(struct task_struct *p, return -EINVAL; return 0; } +static inline bool cpupri_check_rt(void) +{ + return false; +} #endif struct sched_load { diff --git a/kernel/sched/cpupri.c b/kernel/sched/cpupri.c index 1d00cf8c00fa..14225d5d8617 100644 --- a/kernel/sched/cpupri.c +++ b/kernel/sched/cpupri.c @@ -279,3 +279,14 @@ void cpupri_cleanup(struct cpupri *cp) for (i = 0; i < CPUPRI_NR_PRIORITIES; i++) free_cpumask_var(cp->pri_to_cpu[i].mask); } + +/* + * cpupri_check_rt - check if CPU has a RT task + * should be called from rcu-sched read section. + */ +bool cpupri_check_rt(void) +{ + int cpu = raw_smp_processor_id(); + + return cpu_rq(cpu)->rd->cpupri.cpu_to_pri[cpu] > CPUPRI_NORMAL; +} diff --git a/kernel/softirq.c b/kernel/softirq.c index 39ffd41594ce..9029227e5f57 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -234,6 +234,8 @@ static inline bool lockdep_softirq_start(void) { return false; } static inline void lockdep_softirq_end(bool in_hardirq) { } #endif +#define long_softirq_pending() (local_softirq_pending() & LONG_SOFTIRQ_MASK) +#define defer_for_rt() (long_softirq_pending() && cpupri_check_rt()) asmlinkage __visible void __do_softirq(void) { unsigned long end = jiffies + MAX_SOFTIRQ_TIME; @@ -297,6 +299,7 @@ restart: pending = local_softirq_pending(); if (pending) { if (time_before(jiffies, end) && !need_resched() && + !defer_for_rt() && --max_restart) goto restart; @@ -349,7 +352,7 @@ void irq_enter(void) static inline void invoke_softirq(void) { - if (!force_irqthreads) { + if (!force_irqthreads && !defer_for_rt()) { #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK /* * We can safely execute softirq on the current stack if |