diff options
Diffstat (limited to 'features/rt/sched-Add-support-for-lazy-preemption.patch')
| -rw-r--r-- | features/rt/sched-Add-support-for-lazy-preemption.patch | 690 |
1 files changed, 690 insertions, 0 deletions
diff --git a/features/rt/sched-Add-support-for-lazy-preemption.patch b/features/rt/sched-Add-support-for-lazy-preemption.patch new file mode 100644 index 00000000..e3b28534 --- /dev/null +++ b/features/rt/sched-Add-support-for-lazy-preemption.patch @@ -0,0 +1,690 @@ +From 4ea3d1a1ba58c951bbfc4f5e3592823f3fcd2d4a Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Fri, 26 Oct 2012 18:50:54 +0100 +Subject: [PATCH 163/191] sched: Add support for lazy preemption + +It has become an obsession to mitigate the determinism vs. throughput +loss of RT. Looking at the mainline semantics of preemption points +gives a hint why RT sucks throughput wise for ordinary SCHED_OTHER +tasks. One major issue is the wakeup of tasks which are right away +preempting the waking task while the waking task holds a lock on which +the woken task will block right after having preempted the wakee. In +mainline this is prevented due to the implicit preemption disable of +spin/rw_lock held regions. On RT this is not possible due to the fully +preemptible nature of sleeping spinlocks. + +Though for a SCHED_OTHER task preempting another SCHED_OTHER task this +is really not a correctness issue. RT folks are concerned about +SCHED_FIFO/RR tasks preemption and not about the purely fairness +driven SCHED_OTHER preemption latencies. + +So I introduced a lazy preemption mechanism which only applies to +SCHED_OTHER tasks preempting another SCHED_OTHER task. Aside of the +existing preempt_count each tasks sports now a preempt_lazy_count +which is manipulated on lock acquiry and release. This is slightly +incorrect as for lazyness reasons I coupled this on +migrate_disable/enable so some other mechanisms get the same treatment +(e.g. get_cpu_light). + +Now on the scheduler side instead of setting NEED_RESCHED this sets +NEED_RESCHED_LAZY in case of a SCHED_OTHER/SCHED_OTHER preemption and +therefor allows to exit the waking task the lock held region before +the woken task preempts. That also works better for cross CPU wakeups +as the other side can stay in the adaptive spinning loop. + +For RT class preemption there is no change. This simply sets +NEED_RESCHED and forgoes the lazy preemption counter. + + Initial test do not expose any observable latency increasement, but +history shows that I've been proven wrong before :) + +The lazy preemption mode is per default on, but with +CONFIG_SCHED_DEBUG enabled it can be disabled via: + + # echo NO_PREEMPT_LAZY >/sys/kernel/debug/sched_features + +and reenabled via + + # echo PREEMPT_LAZY >/sys/kernel/debug/sched_features + +The test results so far are very machine and workload dependent, but +there is a clear trend that it enhances the non RT workload +performance. + +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +--- + include/linux/preempt.h | 54 ++++++++++++++++++++++-- + include/linux/sched.h | 38 +++++++++++++++++ + include/linux/thread_info.h | 12 +++++- + include/linux/trace_events.h | 5 ++- + kernel/Kconfig.preempt | 6 +++ + kernel/sched/core.c | 82 +++++++++++++++++++++++++++++++++++- + kernel/sched/fair.c | 16 +++---- + kernel/sched/features.h | 3 ++ + kernel/sched/sched.h | 9 ++++ + kernel/trace/trace.c | 50 +++++++++++++--------- + kernel/trace/trace_events.c | 1 + + kernel/trace/trace_output.c | 14 +++++- + 12 files changed, 254 insertions(+), 36 deletions(-) + +diff --git a/include/linux/preempt.h b/include/linux/preempt.h +index fb140e00f74d..af39859f02ee 100644 +--- a/include/linux/preempt.h ++++ b/include/linux/preempt.h +@@ -174,6 +174,20 @@ extern void preempt_count_sub(int val); + #define preempt_count_inc() preempt_count_add(1) + #define preempt_count_dec() preempt_count_sub(1) + ++#ifdef CONFIG_PREEMPT_LAZY ++#define add_preempt_lazy_count(val) do { preempt_lazy_count() += (val); } while (0) ++#define sub_preempt_lazy_count(val) do { preempt_lazy_count() -= (val); } while (0) ++#define inc_preempt_lazy_count() add_preempt_lazy_count(1) ++#define dec_preempt_lazy_count() sub_preempt_lazy_count(1) ++#define preempt_lazy_count() (current_thread_info()->preempt_lazy_count) ++#else ++#define add_preempt_lazy_count(val) do { } while (0) ++#define sub_preempt_lazy_count(val) do { } while (0) ++#define inc_preempt_lazy_count() do { } while (0) ++#define dec_preempt_lazy_count() do { } while (0) ++#define preempt_lazy_count() (0) ++#endif ++ + #ifdef CONFIG_PREEMPT_COUNT + + #define preempt_disable() \ +@@ -182,6 +196,12 @@ do { \ + barrier(); \ + } while (0) + ++#define preempt_lazy_disable() \ ++do { \ ++ inc_preempt_lazy_count(); \ ++ barrier(); \ ++} while (0) ++ + #define sched_preempt_enable_no_resched() \ + do { \ + barrier(); \ +@@ -219,6 +239,18 @@ do { \ + __preempt_schedule(); \ + } while (0) + ++/* ++ * open code preempt_check_resched() because it is not exported to modules and ++ * used by local_unlock() or bpf_enable_instrumentation(). ++ */ ++#define preempt_lazy_enable() \ ++do { \ ++ dec_preempt_lazy_count(); \ ++ barrier(); \ ++ if (should_resched(0)) \ ++ __preempt_schedule(); \ ++} while (0) ++ + #else /* !CONFIG_PREEMPTION */ + #define preempt_enable() \ + do { \ +@@ -226,6 +258,12 @@ do { \ + preempt_count_dec(); \ + } while (0) + ++#define preempt_lazy_enable() \ ++do { \ ++ dec_preempt_lazy_count(); \ ++ barrier(); \ ++} while (0) ++ + #define preempt_enable_notrace() \ + do { \ + barrier(); \ +@@ -267,6 +305,9 @@ do { \ + #define preempt_check_resched_rt() barrier() + #define preemptible() 0 + ++#define preempt_lazy_disable() barrier() ++#define preempt_lazy_enable() barrier() ++ + #endif /* CONFIG_PREEMPT_COUNT */ + + #ifdef MODULE +@@ -285,7 +326,7 @@ do { \ + } while (0) + #define preempt_fold_need_resched() \ + do { \ +- if (tif_need_resched()) \ ++ if (tif_need_resched_now()) \ + set_preempt_need_resched(); \ + } while (0) + +@@ -413,8 +454,15 @@ extern void migrate_enable(void); + + #else + +-static inline void migrate_disable(void) { } +-static inline void migrate_enable(void) { } ++static inline void migrate_disable(void) ++{ ++ preempt_lazy_disable(); ++} ++ ++static inline void migrate_enable(void) ++{ ++ preempt_lazy_enable(); ++} + + #endif /* CONFIG_SMP */ + +diff --git a/include/linux/sched.h b/include/linux/sched.h +index dab770a030bd..8e566b8049aa 100644 +--- a/include/linux/sched.h ++++ b/include/linux/sched.h +@@ -1880,6 +1880,44 @@ static inline int test_tsk_need_resched(struct task_struct *tsk) + return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED)); + } + ++#ifdef CONFIG_PREEMPT_LAZY ++static inline void set_tsk_need_resched_lazy(struct task_struct *tsk) ++{ ++ set_tsk_thread_flag(tsk,TIF_NEED_RESCHED_LAZY); ++} ++ ++static inline void clear_tsk_need_resched_lazy(struct task_struct *tsk) ++{ ++ clear_tsk_thread_flag(tsk,TIF_NEED_RESCHED_LAZY); ++} ++ ++static inline int test_tsk_need_resched_lazy(struct task_struct *tsk) ++{ ++ return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED_LAZY)); ++} ++ ++static inline int need_resched_lazy(void) ++{ ++ return test_thread_flag(TIF_NEED_RESCHED_LAZY); ++} ++ ++static inline int need_resched_now(void) ++{ ++ return test_thread_flag(TIF_NEED_RESCHED); ++} ++ ++#else ++static inline void clear_tsk_need_resched_lazy(struct task_struct *tsk) { } ++static inline int need_resched_lazy(void) { return 0; } ++ ++static inline int need_resched_now(void) ++{ ++ return test_thread_flag(TIF_NEED_RESCHED); ++} ++ ++#endif ++ ++ + static inline bool __task_is_stopped_or_traced(struct task_struct *task) + { + if (task->state & (__TASK_STOPPED | __TASK_TRACED)) +diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h +index 9b2158c69275..8d1cac4052f2 100644 +--- a/include/linux/thread_info.h ++++ b/include/linux/thread_info.h +@@ -149,7 +149,17 @@ static inline int test_ti_thread_flag(struct thread_info *ti, int flag) + clear_ti_thread_flag(task_thread_info(t), TIF_##fl) + #endif /* !CONFIG_GENERIC_ENTRY */ + +-#define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED) ++#ifdef CONFIG_PREEMPT_LAZY ++#define tif_need_resched() (test_thread_flag(TIF_NEED_RESCHED) || \ ++ test_thread_flag(TIF_NEED_RESCHED_LAZY)) ++#define tif_need_resched_now() (test_thread_flag(TIF_NEED_RESCHED)) ++#define tif_need_resched_lazy() test_thread_flag(TIF_NEED_RESCHED_LAZY) ++ ++#else ++#define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED) ++#define tif_need_resched_now() test_thread_flag(TIF_NEED_RESCHED) ++#define tif_need_resched_lazy() 0 ++#endif + + #ifndef CONFIG_HAVE_ARCH_WITHIN_STACK_FRAMES + static inline int arch_within_stack_frames(const void * const stack, +diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h +index 1048965a8750..9e4bc12bb826 100644 +--- a/include/linux/trace_events.h ++++ b/include/linux/trace_events.h +@@ -70,6 +70,7 @@ struct trace_entry { + unsigned char preempt_count; + int pid; + unsigned char migrate_disable; ++ unsigned char preempt_lazy_count; + }; + + #define TRACE_EVENT_TYPE_MAX \ +@@ -159,9 +160,10 @@ static inline void tracing_generic_entry_update(struct trace_entry *entry, + { + entry->preempt_count = trace_ctx & 0xff; + entry->migrate_disable = (trace_ctx >> 8) & 0xff; ++ entry->preempt_lazy_count = (trace_ctx >> 16) & 0xff; + entry->pid = current->pid; + entry->type = type; +- entry->flags = trace_ctx >> 16; ++ entry->flags = trace_ctx >> 24; + } + + unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status); +@@ -174,6 +176,7 @@ enum trace_flag_type { + TRACE_FLAG_SOFTIRQ = 0x10, + TRACE_FLAG_PREEMPT_RESCHED = 0x20, + TRACE_FLAG_NMI = 0x40, ++ TRACE_FLAG_NEED_RESCHED_LAZY = 0x80, + }; + + #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT +diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt +index c8e516f6db20..90837a6cb2e8 100644 +--- a/kernel/Kconfig.preempt ++++ b/kernel/Kconfig.preempt +@@ -1,5 +1,11 @@ + # SPDX-License-Identifier: GPL-2.0-only + ++config HAVE_PREEMPT_LAZY ++ bool ++ ++config PREEMPT_LAZY ++ def_bool y if HAVE_PREEMPT_LAZY && PREEMPT_RT ++ + choice + prompt "Preemption Model" + default PREEMPT_NONE +diff --git a/kernel/sched/core.c b/kernel/sched/core.c +index 5dc7a8edf093..46f2d26a7108 100644 +--- a/kernel/sched/core.c ++++ b/kernel/sched/core.c +@@ -647,6 +647,48 @@ void resched_curr(struct rq *rq) + trace_sched_wake_idle_without_ipi(cpu); + } + ++#ifdef CONFIG_PREEMPT_LAZY ++ ++static int tsk_is_polling(struct task_struct *p) ++{ ++#ifdef TIF_POLLING_NRFLAG ++ return test_tsk_thread_flag(p, TIF_POLLING_NRFLAG); ++#else ++ return 0; ++#endif ++} ++ ++void resched_curr_lazy(struct rq *rq) ++{ ++ struct task_struct *curr = rq->curr; ++ int cpu; ++ ++ if (!sched_feat(PREEMPT_LAZY)) { ++ resched_curr(rq); ++ return; ++ } ++ ++ lockdep_assert_held(&rq->lock); ++ ++ if (test_tsk_need_resched(curr)) ++ return; ++ ++ if (test_tsk_need_resched_lazy(curr)) ++ return; ++ ++ set_tsk_need_resched_lazy(curr); ++ ++ cpu = cpu_of(rq); ++ if (cpu == smp_processor_id()) ++ return; ++ ++ /* NEED_RESCHED_LAZY must be visible before we test polling */ ++ smp_mb(); ++ if (!tsk_is_polling(curr)) ++ smp_send_reschedule(cpu); ++} ++#endif ++ + void resched_cpu(int cpu) + { + struct rq *rq = cpu_rq(cpu); +@@ -1778,6 +1820,7 @@ void migrate_disable(void) + preempt_disable(); + this_rq()->nr_pinned++; + p->migration_disabled = 1; ++ preempt_lazy_disable(); + preempt_enable(); + } + EXPORT_SYMBOL_GPL(migrate_disable); +@@ -1806,6 +1849,7 @@ void migrate_enable(void) + barrier(); + p->migration_disabled = 0; + this_rq()->nr_pinned--; ++ preempt_lazy_enable(); + preempt_enable(); + } + EXPORT_SYMBOL_GPL(migrate_enable); +@@ -3851,6 +3895,9 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p) + p->on_cpu = 0; + #endif + init_task_preempt_count(p); ++#ifdef CONFIG_HAVE_PREEMPT_LAZY ++ task_thread_info(p)->preempt_lazy_count = 0; ++#endif + #ifdef CONFIG_SMP + plist_node_init(&p->pushable_tasks, MAX_PRIO); + RB_CLEAR_NODE(&p->pushable_dl_tasks); +@@ -5104,6 +5151,7 @@ static void __sched notrace __schedule(bool preempt, bool spinning_lock) + + next = pick_next_task(rq, prev, &rf); + clear_tsk_need_resched(prev); ++ clear_tsk_need_resched_lazy(prev); + clear_preempt_need_resched(); + + if (likely(prev != next)) { +@@ -5303,6 +5351,30 @@ static void __sched notrace preempt_schedule_common(void) + } while (need_resched()); + } + ++#ifdef CONFIG_PREEMPT_LAZY ++/* ++ * If TIF_NEED_RESCHED is then we allow to be scheduled away since this is ++ * set by a RT task. Oterwise we try to avoid beeing scheduled out as long as ++ * preempt_lazy_count counter >0. ++ */ ++static __always_inline int preemptible_lazy(void) ++{ ++ if (test_thread_flag(TIF_NEED_RESCHED)) ++ return 1; ++ if (current_thread_info()->preempt_lazy_count) ++ return 0; ++ return 1; ++} ++ ++#else ++ ++static inline int preemptible_lazy(void) ++{ ++ return 1; ++} ++ ++#endif ++ + #ifdef CONFIG_PREEMPTION + /* + * This is the entry point to schedule() from in-kernel preemption +@@ -5316,7 +5388,8 @@ asmlinkage __visible void __sched notrace preempt_schedule(void) + */ + if (likely(!preemptible())) + return; +- ++ if (!preemptible_lazy()) ++ return; + preempt_schedule_common(); + } + NOKPROBE_SYMBOL(preempt_schedule); +@@ -5362,6 +5435,9 @@ asmlinkage __visible void __sched notrace preempt_schedule_notrace(void) + if (likely(!preemptible())) + return; + ++ if (!preemptible_lazy()) ++ return; ++ + do { + /* + * Because the function tracer can trace preempt_count_sub() +@@ -7554,7 +7630,9 @@ void init_idle(struct task_struct *idle, int cpu) + + /* Set the preempt count _outside_ the spinlocks! */ + init_idle_preempt_count(idle, cpu); +- ++#ifdef CONFIG_HAVE_PREEMPT_LAZY ++ task_thread_info(idle)->preempt_lazy_count = 0; ++#endif + /* + * The idle tasks have their own, simple scheduling class: + */ +diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c +index 794c2cb945f8..f354c6d370d7 100644 +--- a/kernel/sched/fair.c ++++ b/kernel/sched/fair.c +@@ -4365,7 +4365,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) + ideal_runtime = sched_slice(cfs_rq, curr); + delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; + if (delta_exec > ideal_runtime) { +- resched_curr(rq_of(cfs_rq)); ++ resched_curr_lazy(rq_of(cfs_rq)); + /* + * The current task ran long enough, ensure it doesn't get + * re-elected due to buddy favours. +@@ -4389,7 +4389,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) + return; + + if (delta > ideal_runtime) +- resched_curr(rq_of(cfs_rq)); ++ resched_curr_lazy(rq_of(cfs_rq)); + } + + static void +@@ -4532,7 +4532,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) + * validating it and just reschedule. + */ + if (queued) { +- resched_curr(rq_of(cfs_rq)); ++ resched_curr_lazy(rq_of(cfs_rq)); + return; + } + /* +@@ -4669,7 +4669,7 @@ static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) + * hierarchy can be throttled + */ + if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr)) +- resched_curr(rq_of(cfs_rq)); ++ resched_curr_lazy(rq_of(cfs_rq)); + } + + static __always_inline +@@ -5413,7 +5413,7 @@ static void hrtick_start_fair(struct rq *rq, struct task_struct *p) + + if (delta < 0) { + if (task_current(rq, p)) +- resched_curr(rq); ++ resched_curr_lazy(rq); + return; + } + hrtick_start(rq, delta); +@@ -6988,7 +6988,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ + return; + + preempt: +- resched_curr(rq); ++ resched_curr_lazy(rq); + /* + * Only set the backward buddy when the current task is still + * on the rq. This can happen when a wakeup gets interleaved +@@ -10775,7 +10775,7 @@ static void task_fork_fair(struct task_struct *p) + * 'current' within the tree based on its new key value. + */ + swap(curr->vruntime, se->vruntime); +- resched_curr(rq); ++ resched_curr_lazy(rq); + } + + se->vruntime -= cfs_rq->min_vruntime; +@@ -10802,7 +10802,7 @@ prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio) + */ + if (task_current(rq, p)) { + if (p->prio > oldprio) +- resched_curr(rq); ++ resched_curr_lazy(rq); + } else + check_preempt_curr(rq, p, 0); + } +diff --git a/kernel/sched/features.h b/kernel/sched/features.h +index b47967d00570..c490f2c902ae 100644 +--- a/kernel/sched/features.h ++++ b/kernel/sched/features.h +@@ -48,6 +48,9 @@ SCHED_FEAT(NONTASK_CAPACITY, true) + + #ifdef CONFIG_PREEMPT_RT + SCHED_FEAT(TTWU_QUEUE, false) ++# ifdef CONFIG_PREEMPT_LAZY ++SCHED_FEAT(PREEMPT_LAZY, true) ++# endif + #else + + /* +diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h +index b65a4e244a77..178fe64154e7 100644 +--- a/kernel/sched/sched.h ++++ b/kernel/sched/sched.h +@@ -2015,6 +2015,15 @@ extern void reweight_task(struct task_struct *p, int prio); + extern void resched_curr(struct rq *rq); + extern void resched_cpu(int cpu); + ++#ifdef CONFIG_PREEMPT_LAZY ++extern void resched_curr_lazy(struct rq *rq); ++#else ++static inline void resched_curr_lazy(struct rq *rq) ++{ ++ resched_curr(rq); ++} ++#endif ++ + extern struct rt_bandwidth def_rt_bandwidth; + extern void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime); + +diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c +index 55bcdaedf7a8..9836ab9d22bb 100644 +--- a/kernel/trace/trace.c ++++ b/kernel/trace/trace.c +@@ -2614,8 +2614,16 @@ unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status) + trace_flags |= TRACE_FLAG_NEED_RESCHED; + if (test_preempt_need_resched()) + trace_flags |= TRACE_FLAG_PREEMPT_RESCHED; +- return (trace_flags << 16) | (pc & 0xff) | +- (migration_disable_value() & 0xff) << 8; ++ ++#ifdef CONFIG_PREEMPT_LAZY ++ if (need_resched_lazy()) ++ trace_flags |= TRACE_FLAG_NEED_RESCHED_LAZY; ++#endif ++ ++ return (pc & 0xff) | ++ (migration_disable_value() & 0xff) << 8 | ++ (preempt_lazy_count() & 0xff) << 16 | ++ (trace_flags << 24); + } + + struct ring_buffer_event * +@@ -3875,15 +3883,17 @@ unsigned long trace_total_entries(struct trace_array *tr) + + static void print_lat_help_header(struct seq_file *m) + { +- seq_puts(m, "# _------=> CPU# \n" +- "# / _-----=> irqs-off \n" +- "# | / _----=> need-resched \n" +- "# || / _---=> hardirq/softirq \n" +- "# ||| / _--=> preempt-depth \n" +- "# |||| / _-=> migrate-disable \n" +- "# ||||| / delay \n" +- "# cmd pid |||||| time | caller \n" +- "# \\ / |||||| \\ | / \n"); ++ seq_puts(m, "# _--------=> CPU# \n" ++ "# / _-------=> irqs-off \n" ++ "# | / _------=> need-resched \n" ++ "# || / _-----=> need-resched-lazy\n" ++ "# ||| / _----=> hardirq/softirq \n" ++ "# |||| / _---=> preempt-depth \n" ++ "# ||||| / _--=> preempt-lazy-depth\n" ++ "# |||||| / _-=> migrate-disable \n" ++ "# ||||||| / delay \n" ++ "# cmd pid |||||||| time | caller \n" ++ "# \\ / |||||||| \\ | / \n"); + } + + static void print_event_info(struct array_buffer *buf, struct seq_file *m) +@@ -3917,14 +3927,16 @@ static void print_func_help_header_irq(struct array_buffer *buf, struct seq_file + + print_event_info(buf, m); + +- seq_printf(m, "# %.*s _-----=> irqs-off\n", prec, space); +- seq_printf(m, "# %.*s / _----=> need-resched\n", prec, space); +- seq_printf(m, "# %.*s| / _---=> hardirq/softirq\n", prec, space); +- seq_printf(m, "# %.*s|| / _--=> preempt-depth\n", prec, space); +- seq_printf(m, "# %.*s||| / _-=> migrate-disable\n", prec, space); +- seq_printf(m, "# %.*s|||| / delay\n", prec, space); +- seq_printf(m, "# TASK-PID %.*s CPU# ||||| TIMESTAMP FUNCTION\n", prec, " TGID "); +- seq_printf(m, "# | | %.*s | ||||| | |\n", prec, " | "); ++ seq_printf(m, "# %.*s _-------=> irqs-off\n", prec, space); ++ seq_printf(m, "# %.*s / _------=> need-resched\n", prec, space); ++ seq_printf(m, "# %.*s| / _-----=> need-resched-lazy\n", prec, space); ++ seq_printf(m, "# %.*s|| / _----=> hardirq/softirq\n", prec, space); ++ seq_printf(m, "# %.*s||| / _---=> preempt-depth\n", prec, space); ++ seq_printf(m, "# %.*s|||| / _--=> preempt-lazy-depth\n", prec, space); ++ seq_printf(m, "# %.*s||||| / _-=> migrate-disable\n", prec, space); ++ seq_printf(m, "# %.*s|||||| / delay\n", prec, space); ++ seq_printf(m, "# TASK-PID %.*s CPU# ||||||| TIMESTAMP FUNCTION\n", prec, " TGID "); ++ seq_printf(m, "# | | %.*s | ||||||| | |\n", prec, " | "); + } + + void +diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c +index ba0b9edd652d..39fa2a7a8b03 100644 +--- a/kernel/trace/trace_events.c ++++ b/kernel/trace/trace_events.c +@@ -184,6 +184,7 @@ static int trace_define_common_fields(void) + __common_field(unsigned char, preempt_count); + __common_field(int, pid); + __common_field(unsigned char, migrate_disable); ++ __common_field(unsigned char, preempt_lazy_count); + + return ret; + } +diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c +index 5e32edb8a90a..af85aec1e887 100644 +--- a/kernel/trace/trace_output.c ++++ b/kernel/trace/trace_output.c +@@ -451,6 +451,7 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry) + { + char hardsoft_irq; + char need_resched; ++ char need_resched_lazy; + char irqs_off; + int hardirq; + int softirq; +@@ -481,6 +482,9 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry) + break; + } + ++ need_resched_lazy = ++ (entry->flags & TRACE_FLAG_NEED_RESCHED_LAZY) ? 'L' : '.'; ++ + hardsoft_irq = + (nmi && hardirq) ? 'Z' : + nmi ? 'z' : +@@ -489,14 +493,20 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry) + softirq ? 's' : + '.' ; + +- trace_seq_printf(s, "%c%c%c", +- irqs_off, need_resched, hardsoft_irq); ++ trace_seq_printf(s, "%c%c%c%c", ++ irqs_off, need_resched, need_resched_lazy, ++ hardsoft_irq); + + if (entry->preempt_count) + trace_seq_printf(s, "%x", entry->preempt_count); + else + trace_seq_putc(s, '.'); + ++ if (entry->preempt_lazy_count) ++ trace_seq_printf(s, "%x", entry->preempt_lazy_count); ++ else ++ trace_seq_putc(s, '.'); ++ + if (entry->migrate_disable) + trace_seq_printf(s, "%x", entry->migrate_disable); + else +-- +2.19.1 + |