diff options
Diffstat (limited to 'debian/patches-rt/0032-sched-Add-support-for-lazy-preemption.patch')
| -rw-r--r-- | debian/patches-rt/0032-sched-Add-support-for-lazy-preemption.patch | 714 |
1 files changed, 714 insertions, 0 deletions
diff --git a/debian/patches-rt/0032-sched-Add-support-for-lazy-preemption.patch b/debian/patches-rt/0032-sched-Add-support-for-lazy-preemption.patch new file mode 100644 index 000000000..54c21bbb9 --- /dev/null +++ b/debian/patches-rt/0032-sched-Add-support-for-lazy-preemption.patch @@ -0,0 +1,714 @@ +From 87194c420f8ef3b1a8b9b63ae640180e2414e8c4 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Fri, 26 Oct 2012 18:50:54 +0100 +Subject: [PATCH 32/62] sched: Add support for lazy preemption +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.1/older/patches-6.1.69-rt21.tar.xz + +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 | 37 +++++++++++++++++ + include/linux/thread_info.h | 12 +++++- + include/linux/trace_events.h | 10 ++++- + kernel/Kconfig.preempt | 6 +++ + kernel/sched/core.c | 79 +++++++++++++++++++++++++++++++++++- + 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 | 18 +++++++- + 12 files changed, 260 insertions(+), 35 deletions(-) + +diff --git a/include/linux/preempt.h b/include/linux/preempt.h +index 8cfcc5d45451..9fc4c4bb320f 100644 +--- a/include/linux/preempt.h ++++ b/include/linux/preempt.h +@@ -207,6 +207,20 @@ 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() \ +@@ -215,6 +229,12 @@ do { \ + barrier(); \ + } while (0) + ++#define preempt_lazy_disable() \ ++do { \ ++ inc_preempt_lazy_count(); \ ++ barrier(); \ ++} while (0) ++ + #define sched_preempt_enable_no_resched() \ + do { \ + barrier(); \ +@@ -246,6 +266,18 @@ 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 { \ +@@ -253,6 +285,12 @@ do { \ + preempt_count_dec(); \ + } while (0) + ++#define preempt_lazy_enable() \ ++do { \ ++ dec_preempt_lazy_count(); \ ++ barrier(); \ ++} while (0) ++ + #define preempt_enable_notrace() \ + do { \ + barrier(); \ +@@ -293,6 +331,9 @@ do { \ + #define preempt_enable_notrace() barrier() + #define preemptible() 0 + ++#define preempt_lazy_disable() barrier() ++#define preempt_lazy_enable() barrier() ++ + #endif /* CONFIG_PREEMPT_COUNT */ + + #ifdef MODULE +@@ -311,7 +352,7 @@ do { \ + } while (0) + #define preempt_fold_need_resched() \ + do { \ +- if (tif_need_resched()) \ ++ if (tif_need_resched_now()) \ + set_preempt_need_resched(); \ + } while (0) + +@@ -427,8 +468,15 @@ 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 0cac69902ec5..67ec36dbfacf 100644 +--- a/include/linux/sched.h ++++ b/include/linux/sched.h +@@ -2061,6 +2061,43 @@ 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 ++ + /* + * cond_resched() and cond_resched_lock(): latency reduction via + * explicit rescheduling in places that are safe. The return +diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h +index 9f392ec76f2b..779e0e96b9cb 100644 +--- a/include/linux/thread_info.h ++++ b/include/linux/thread_info.h +@@ -177,7 +177,17 @@ static __always_inline unsigned long read_ti_thread_flags(struct thread_info *ti + 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 c8b5e9781d01..743b1183d184 100644 +--- a/include/linux/trace_events.h ++++ b/include/linux/trace_events.h +@@ -70,6 +70,7 @@ struct trace_entry { + unsigned char flags; + unsigned char preempt_count; + int pid; ++ 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, + unsigned int trace_ctx) + { + entry->preempt_count = trace_ctx & 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); +@@ -172,7 +174,13 @@ enum trace_flag_type { + TRACE_FLAG_NEED_RESCHED = 0x04, + TRACE_FLAG_HARDIRQ = 0x08, + TRACE_FLAG_SOFTIRQ = 0x10, ++#ifdef CONFIG_PREEMPT_LAZY ++ TRACE_FLAG_PREEMPT_RESCHED = 0x00, ++ TRACE_FLAG_NEED_RESCHED_LAZY = 0x20, ++#else ++ TRACE_FLAG_NEED_RESCHED_LAZY = 0x00, + TRACE_FLAG_PREEMPT_RESCHED = 0x20, ++#endif + TRACE_FLAG_NMI = 0x40, + TRACE_FLAG_BH_OFF = 0x80, + }; +diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt +index c2f1fd95a821..260c08efeb48 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 ++ + config PREEMPT_NONE_BUILD + bool + +diff --git a/kernel/sched/core.c b/kernel/sched/core.c +index 6bd06122850a..b72fc7d336e4 100644 +--- a/kernel/sched/core.c ++++ b/kernel/sched/core.c +@@ -1040,6 +1040,46 @@ 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; ++ } ++ ++ 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); +@@ -2224,6 +2264,7 @@ void migrate_disable(void) + preempt_disable(); + this_rq()->nr_pinned++; + p->migration_disabled = 1; ++ preempt_lazy_disable(); + preempt_enable(); + } + EXPORT_SYMBOL_GPL(migrate_disable); +@@ -2255,6 +2296,7 @@ void migrate_enable(void) + barrier(); + p->migration_disabled = 0; + this_rq()->nr_pinned--; ++ preempt_lazy_enable(); + preempt_enable(); + } + EXPORT_SYMBOL_GPL(migrate_enable); +@@ -4722,6 +4764,9 @@ 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); +@@ -6592,6 +6637,7 @@ static void __sched notrace __schedule(unsigned int sched_mode) + + next = pick_next_task(rq, prev, &rf); + clear_tsk_need_resched(prev); ++ clear_tsk_need_resched_lazy(prev); + clear_preempt_need_resched(); + #ifdef CONFIG_SCHED_DEBUG + rq->last_seen_need_resched_ns = 0; +@@ -6806,6 +6852,30 @@ 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 +@@ -6819,6 +6889,8 @@ asmlinkage __visible void __sched notrace preempt_schedule(void) + */ + if (likely(!preemptible())) + return; ++ if (!preemptible_lazy()) ++ return; + preempt_schedule_common(); + } + NOKPROBE_SYMBOL(preempt_schedule); +@@ -6866,6 +6938,9 @@ 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() +@@ -9131,7 +9206,9 @@ void __init 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 2558ab9033be..2dc35af7b5a6 100644 +--- a/kernel/sched/fair.c ++++ b/kernel/sched/fair.c +@@ -4914,7 +4914,7 @@ 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. +@@ -4938,7 +4938,7 @@ 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 +@@ -5084,7 +5084,7 @@ 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; + } + /* +@@ -5233,7 +5233,7 @@ 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 +@@ -5984,7 +5984,7 @@ 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); +@@ -7712,7 +7712,7 @@ 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 +@@ -11877,7 +11877,7 @@ 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; +@@ -11904,7 +11904,7 @@ 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 ee7f23c76bd3..e13090e33f3c 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 b62d53d7c264..f2577f511a41 100644 +--- a/kernel/sched/sched.h ++++ b/kernel/sched/sched.h +@@ -2350,6 +2350,15 @@ 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); + extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq); +diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c +index 87eca95b57fb..462564d652be 100644 +--- a/kernel/trace/trace.c ++++ b/kernel/trace/trace.c +@@ -2616,11 +2616,19 @@ unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status) + if (softirq_count() >> (SOFTIRQ_SHIFT + 1)) + trace_flags |= TRACE_FLAG_BH_OFF; + +- if (tif_need_resched()) ++ if (tif_need_resched_now()) + trace_flags |= TRACE_FLAG_NEED_RESCHED; ++#ifdef CONFIG_PREEMPT_LAZY ++ /* Run out of bits. Share the LAZY and PREEMPT_RESCHED */ ++ if (need_resched_lazy()) ++ trace_flags |= TRACE_FLAG_NEED_RESCHED_LAZY; ++#else + if (test_preempt_need_resched()) + trace_flags |= TRACE_FLAG_PREEMPT_RESCHED; +- return (trace_flags << 16) | (min_t(unsigned int, pc & 0xff, 0xf)) | ++#endif ++ ++ return (trace_flags << 24) | (min_t(unsigned int, pc & 0xff, 0xf)) | ++ (preempt_lazy_count() & 0xff) << 16 | + (min_t(unsigned int, migration_disable_value(), 0xf)) << 4; + } + +@@ -4212,15 +4220,17 @@ 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/BH-disabled\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/BH-disabled\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) +@@ -4254,14 +4264,16 @@ 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/BH-disabled\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/BH-disabled\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 a6d2f99f847d..493c3f9cf01a 100644 +--- a/kernel/trace/trace_events.c ++++ b/kernel/trace/trace_events.c +@@ -208,6 +208,7 @@ static int trace_define_common_fields(void) + /* Holds both preempt_count and migrate_disable */ + __common_field(unsigned char, preempt_count); + __common_field(int, pid); ++ __common_field(unsigned char, preempt_lazy_count); + + return ret; + } +diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c +index 5cd4fb656306..3c227e2843ae 100644 +--- a/kernel/trace/trace_output.c ++++ b/kernel/trace/trace_output.c +@@ -442,6 +442,7 @@ 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; +@@ -462,20 +463,27 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry) + + switch (entry->flags & (TRACE_FLAG_NEED_RESCHED | + TRACE_FLAG_PREEMPT_RESCHED)) { ++#ifndef CONFIG_PREEMPT_LAZY + case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_PREEMPT_RESCHED: + need_resched = 'N'; + break; ++#endif + case TRACE_FLAG_NEED_RESCHED: + need_resched = 'n'; + break; ++#ifndef CONFIG_PREEMPT_LAZY + case TRACE_FLAG_PREEMPT_RESCHED: + need_resched = 'p'; + break; ++#endif + default: + need_resched = '.'; + break; + } + ++ need_resched_lazy = ++ (entry->flags & TRACE_FLAG_NEED_RESCHED_LAZY) ? 'L' : '.'; ++ + hardsoft_irq = + (nmi && hardirq) ? 'Z' : + nmi ? 'z' : +@@ -484,14 +492,20 @@ 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 & 0xf) + trace_seq_printf(s, "%x", entry->preempt_count & 0xf); + 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->preempt_count & 0xf0) + trace_seq_printf(s, "%x", entry->preempt_count >> 4); + else +-- +2.43.0 + |