Subject: sched-migrate-disable.patch From: Thomas Gleixner Date: Thu, 16 Jun 2011 13:26:08 +0200 Signed-off-by: Thomas Gleixner --- include/linux/preempt.h | 8 ++++ include/linux/sched.h | 13 +++++-- include/linux/smp.h | 1 kernel/sched.c | 88 +++++++++++++++++++++++++++++++++++++++++++++--- lib/smp_processor_id.c | 6 +-- 5 files changed, 104 insertions(+), 12 deletions(-) Index: linux-3.2/include/linux/preempt.h =================================================================== --- linux-3.2.orig/include/linux/preempt.h +++ linux-3.2/include/linux/preempt.h @@ -108,6 +108,14 @@ do { \ #endif /* CONFIG_PREEMPT_COUNT */ +#ifdef CONFIG_SMP +extern void migrate_disable(void); +extern void migrate_enable(void); +#else +# define migrate_disable() do { } while (0) +# define migrate_enable() do { } while (0) +#endif + #ifdef CONFIG_PREEMPT_RT_FULL # define preempt_disable_rt() preempt_disable() # define preempt_enable_rt() preempt_enable() Index: linux-3.2/include/linux/sched.h =================================================================== --- linux-3.2.orig/include/linux/sched.h +++ linux-3.2/include/linux/sched.h @@ -1259,6 +1259,7 @@ struct task_struct { #endif unsigned int policy; + int migrate_disable; cpumask_t cpus_allowed; #ifdef CONFIG_PREEMPT_RCU @@ -1598,9 +1599,6 @@ struct task_struct { #endif }; -/* Future-safe accessor for struct task_struct's cpus_allowed. */ -#define tsk_cpus_allowed(tsk) (&(tsk)->cpus_allowed) - #ifdef CONFIG_PREEMPT_RT_FULL static inline bool cur_pf_disabled(void) { return current->pagefault_disabled; } #else @@ -2683,6 +2681,15 @@ static inline void set_task_cpu(struct t #endif /* CONFIG_SMP */ +/* Future-safe accessor for struct task_struct's cpus_allowed. */ +static inline const struct cpumask *tsk_cpus_allowed(struct task_struct *p) +{ + if (p->migrate_disable) + return cpumask_of(task_cpu(p)); + + return &p->cpus_allowed; +} + extern long sched_setaffinity(pid_t pid, const struct cpumask *new_mask); extern long sched_getaffinity(pid_t pid, struct cpumask *mask); Index: linux-3.2/include/linux/smp.h =================================================================== --- linux-3.2.orig/include/linux/smp.h +++ linux-3.2/include/linux/smp.h @@ -80,7 +80,6 @@ void __smp_call_function_single(int cpui int smp_call_function_any(const struct cpumask *mask, smp_call_func_t func, void *info, int wait); - /* * Generic and arch helpers */ Index: linux-3.2/kernel/sched.c =================================================================== --- linux-3.2.orig/kernel/sched.c +++ linux-3.2/kernel/sched.c @@ -6224,11 +6224,12 @@ static inline void sched_init_granularit #ifdef CONFIG_SMP void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) { - if (p->sched_class && p->sched_class->set_cpus_allowed) - p->sched_class->set_cpus_allowed(p, new_mask); - + if (!p->migrate_disable) { + if (p->sched_class && p->sched_class->set_cpus_allowed) + p->sched_class->set_cpus_allowed(p, new_mask); + p->rt.nr_cpus_allowed = cpumask_weight(new_mask); + } cpumask_copy(&p->cpus_allowed, new_mask); - p->rt.nr_cpus_allowed = cpumask_weight(new_mask); } /* @@ -6279,7 +6280,7 @@ int set_cpus_allowed_ptr(struct task_str do_set_cpus_allowed(p, new_mask); /* Can the task run on the task's current CPU? If so, we're done */ - if (cpumask_test_cpu(task_cpu(p), new_mask)) + if (cpumask_test_cpu(task_cpu(p), new_mask) || p->migrate_disable) goto out; dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); @@ -6298,6 +6299,83 @@ out: } EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); +void migrate_disable(void) +{ + struct task_struct *p = current; + const struct cpumask *mask; + unsigned long flags; + struct rq *rq; + + preempt_disable(); + if (p->migrate_disable) { + p->migrate_disable++; + preempt_enable(); + return; + } + + pin_current_cpu(); + if (unlikely(!scheduler_running)) { + p->migrate_disable = 1; + preempt_enable(); + return; + } + rq = task_rq_lock(p, &flags); + p->migrate_disable = 1; + mask = tsk_cpus_allowed(p); + + WARN_ON(!cpumask_test_cpu(smp_processor_id(), mask)); + + if (!cpumask_equal(&p->cpus_allowed, mask)) { + if (p->sched_class->set_cpus_allowed) + p->sched_class->set_cpus_allowed(p, mask); + p->rt.nr_cpus_allowed = cpumask_weight(mask); + } + task_rq_unlock(rq, p, &flags); + preempt_enable(); +} +EXPORT_SYMBOL_GPL(migrate_disable); + +void migrate_enable(void) +{ + struct task_struct *p = current; + const struct cpumask *mask; + unsigned long flags; + struct rq *rq; + + WARN_ON_ONCE(p->migrate_disable <= 0); + + preempt_disable(); + if (p->migrate_disable > 1) { + p->migrate_disable--; + preempt_enable(); + return; + } + + if (unlikely(!scheduler_running)) { + p->migrate_disable = 0; + unpin_current_cpu(); + preempt_enable(); + return; + } + + rq = task_rq_lock(p, &flags); + p->migrate_disable = 0; + mask = tsk_cpus_allowed(p); + + WARN_ON(!cpumask_test_cpu(smp_processor_id(), mask)); + + if (!cpumask_equal(&p->cpus_allowed, mask)) { + if (p->sched_class->set_cpus_allowed) + p->sched_class->set_cpus_allowed(p, mask); + p->rt.nr_cpus_allowed = cpumask_weight(mask); + } + + task_rq_unlock(rq, p, &flags); + unpin_current_cpu(); + preempt_enable(); +} +EXPORT_SYMBOL_GPL(migrate_enable); + /* * Move (not current) task off this cpu, onto dest cpu. We're doing * this because either it can't run here any more (set_cpus_allowed() Index: linux-3.2/lib/smp_processor_id.c =================================================================== --- linux-3.2.orig/lib/smp_processor_id.c +++ linux-3.2/lib/smp_processor_id.c @@ -39,9 +39,9 @@ notrace unsigned int debug_smp_processor if (!printk_ratelimit()) goto out_enable; - printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] " - "code: %s/%d\n", - preempt_count() - 1, current->comm, current->pid); + printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x %08x] " + "code: %s/%d\n", preempt_count() - 1, + current->migrate_disable, current->comm, current->pid); print_symbol("caller is %s\n", (long)__builtin_return_address(0)); dump_stack();