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author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-06-20 08:18:35 -1000 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-06-20 08:18:35 -1000 |
commit | a3d5c3460a86f52ea435b3fb98be112bd18faabc (patch) | |
tree | 48a32968b569af0e0f0af1def3effa0770710fea | |
parent | 86c76676cfdbf283f6131d5a2783bed3f3d490ea (diff) | |
parent | 29bb9e5a75684106a37593ad75ec75ff8312731b (diff) | |
download | lwn-a3d5c3460a86f52ea435b3fb98be112bd18faabc.tar.gz lwn-a3d5c3460a86f52ea435b3fb98be112bd18faabc.zip |
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
"Two smaller fixes - plus a context tracking tracing fix that is a bit
bigger"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tracing/context-tracking: Add preempt_schedule_context() for tracing
sched: Fix clear NOHZ_BALANCE_KICK
sched/x86: Construct all sibling maps if smt
-rw-r--r-- | arch/x86/kernel/smpboot.c | 8 | ||||
-rw-r--r-- | include/linux/preempt.h | 18 | ||||
-rw-r--r-- | kernel/context_tracking.c | 40 | ||||
-rw-r--r-- | kernel/sched/core.c | 21 |
4 files changed, 78 insertions, 9 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 9c73b51817e4..bfd348e99369 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -372,15 +372,15 @@ static bool __cpuinit match_mc(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o) void __cpuinit set_cpu_sibling_map(int cpu) { - bool has_mc = boot_cpu_data.x86_max_cores > 1; bool has_smt = smp_num_siblings > 1; + bool has_mp = has_smt || boot_cpu_data.x86_max_cores > 1; struct cpuinfo_x86 *c = &cpu_data(cpu); struct cpuinfo_x86 *o; int i; cpumask_set_cpu(cpu, cpu_sibling_setup_mask); - if (!has_smt && !has_mc) { + if (!has_mp) { cpumask_set_cpu(cpu, cpu_sibling_mask(cpu)); cpumask_set_cpu(cpu, cpu_llc_shared_mask(cpu)); cpumask_set_cpu(cpu, cpu_core_mask(cpu)); @@ -394,7 +394,7 @@ void __cpuinit set_cpu_sibling_map(int cpu) if ((i == cpu) || (has_smt && match_smt(c, o))) link_mask(sibling, cpu, i); - if ((i == cpu) || (has_mc && match_llc(c, o))) + if ((i == cpu) || (has_mp && match_llc(c, o))) link_mask(llc_shared, cpu, i); } @@ -406,7 +406,7 @@ void __cpuinit set_cpu_sibling_map(int cpu) for_each_cpu(i, cpu_sibling_setup_mask) { o = &cpu_data(i); - if ((i == cpu) || (has_mc && match_mc(c, o))) { + if ((i == cpu) || (has_mp && match_mc(c, o))) { link_mask(core, cpu, i); /* diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 87a03c746f17..f5d4723cdb3d 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -33,9 +33,25 @@ do { \ preempt_schedule(); \ } while (0) +#ifdef CONFIG_CONTEXT_TRACKING + +void preempt_schedule_context(void); + +#define preempt_check_resched_context() \ +do { \ + if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \ + preempt_schedule_context(); \ +} while (0) +#else + +#define preempt_check_resched_context() preempt_check_resched() + +#endif /* CONFIG_CONTEXT_TRACKING */ + #else /* !CONFIG_PREEMPT */ #define preempt_check_resched() do { } while (0) +#define preempt_check_resched_context() do { } while (0) #endif /* CONFIG_PREEMPT */ @@ -88,7 +104,7 @@ do { \ do { \ preempt_enable_no_resched_notrace(); \ barrier(); \ - preempt_check_resched(); \ + preempt_check_resched_context(); \ } while (0) #else /* !CONFIG_PREEMPT_COUNT */ diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 85bdde1137eb..383f8231e436 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -70,6 +70,46 @@ void user_enter(void) local_irq_restore(flags); } +#ifdef CONFIG_PREEMPT +/** + * preempt_schedule_context - preempt_schedule called by tracing + * + * The tracing infrastructure uses preempt_enable_notrace to prevent + * recursion and tracing preempt enabling caused by the tracing + * infrastructure itself. But as tracing can happen in areas coming + * from userspace or just about to enter userspace, a preempt enable + * can occur before user_exit() is called. This will cause the scheduler + * to be called when the system is still in usermode. + * + * To prevent this, the preempt_enable_notrace will use this function + * instead of preempt_schedule() to exit user context if needed before + * calling the scheduler. + */ +void __sched notrace preempt_schedule_context(void) +{ + struct thread_info *ti = current_thread_info(); + enum ctx_state prev_ctx; + + if (likely(ti->preempt_count || irqs_disabled())) + return; + + /* + * Need to disable preemption in case user_exit() is traced + * and the tracer calls preempt_enable_notrace() causing + * an infinite recursion. + */ + preempt_disable_notrace(); + prev_ctx = exception_enter(); + preempt_enable_no_resched_notrace(); + + preempt_schedule(); + + preempt_disable_notrace(); + exception_exit(prev_ctx); + preempt_enable_notrace(); +} +EXPORT_SYMBOL_GPL(preempt_schedule_context); +#endif /* CONFIG_PREEMPT */ /** * user_exit - Inform the context tracking that the CPU is diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e1a27f918723..e8b335016c52 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -633,7 +633,19 @@ void wake_up_nohz_cpu(int cpu) static inline bool got_nohz_idle_kick(void) { int cpu = smp_processor_id(); - return idle_cpu(cpu) && test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); + + if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu))) + return false; + + if (idle_cpu(cpu) && !need_resched()) + return true; + + /* + * We can't run Idle Load Balance on this CPU for this time so we + * cancel it and clear NOHZ_BALANCE_KICK + */ + clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); + return false; } #else /* CONFIG_NO_HZ_COMMON */ @@ -1393,8 +1405,9 @@ static void sched_ttwu_pending(void) void scheduler_ipi(void) { - if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick() - && !tick_nohz_full_cpu(smp_processor_id())) + if (llist_empty(&this_rq()->wake_list) + && !tick_nohz_full_cpu(smp_processor_id()) + && !got_nohz_idle_kick()) return; /* @@ -1417,7 +1430,7 @@ void scheduler_ipi(void) /* * Check if someone kicked us for doing the nohz idle load balance. */ - if (unlikely(got_nohz_idle_kick() && !need_resched())) { + if (unlikely(got_nohz_idle_kick())) { this_rq()->idle_balance = 1; raise_softirq_irqoff(SCHED_SOFTIRQ); } |