From 978b0116cd225682a29e3d1d5010319bf2de32c2 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Sat, 6 Sep 2008 20:04:36 +0200 Subject: softirq: allocate less vectors We don't need whole 32 of them, only NR_SOFTIRQS. Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Ingo Molnar --- kernel/softirq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/softirq.c') diff --git a/kernel/softirq.c b/kernel/softirq.c index c506f266a6b..82e32aadedd 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -46,7 +46,7 @@ irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned; EXPORT_SYMBOL(irq_stat); #endif -static struct softirq_action softirq_vec[32] __cacheline_aligned_in_smp; +static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp; static DEFINE_PER_CPU(struct task_struct *, ksoftirqd); -- cgit v1.2.3-70-g09d2 From 8e85b4b553fc932e1c5141feb5fda389b7f5db01 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 2 Oct 2008 10:50:53 +0200 Subject: softirqs, debug: preemption check if a preempt count leaks out of a softirq handler it can be very hard to figure it out. Add a debug check for this. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar --- kernel/softirq.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'kernel/softirq.c') diff --git a/kernel/softirq.c b/kernel/softirq.c index 82e32aadedd..1cf1e2f2c40 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -205,7 +205,18 @@ restart: do { if (pending & 1) { + int prev_count = preempt_count(); + h->action(h); + + if (unlikely(prev_count != preempt_count())) { + printk(KERN_ERR "huh, entered sotfirq %ld %p" + "with preempt_count %08x," + " exited with %08x?\n", h - softirq_vec, + h->action, prev_count, preempt_count()); + preempt_count() = prev_count; + } + rcu_bh_qsctr_inc(cpu); } h++; -- cgit v1.2.3-70-g09d2 From 77af7e3403e7314c47b0c07fbc5e4ef21d939532 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 3 Oct 2008 11:39:46 +0200 Subject: softirq, warning fix: correct a format to avoid a warning MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Last -tip gives this warning: kernel/softirq.c: Dans la fonction «__do_softirq» : kernel/softirq.c:216: attention : format «%ld» expects type «long int», but argument 2 has type «int» This patch corrects the format type, and a small mistake in the "softirq" word. Signed-off-by: Frederic Weisbecker Signed-off-by: Ingo Molnar --- kernel/softirq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/softirq.c') diff --git a/kernel/softirq.c b/kernel/softirq.c index 1cf1e2f2c40..be7a8292f99 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -210,7 +210,7 @@ restart: h->action(h); if (unlikely(prev_count != preempt_count())) { - printk(KERN_ERR "huh, entered sotfirq %ld %p" + printk(KERN_ERR "huh, entered softirq %d %p" "with preempt_count %08x," " exited with %08x?\n", h - softirq_vec, h->action, prev_count, preempt_count()); -- cgit v1.2.3-70-g09d2 From 1c95e1b69073cff5ff179e592fa1a1e182c78a17 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 16 Oct 2008 15:32:46 -0700 Subject: Fix kernel/softirq.c printk format warning properly This fixes the broken 77af7e3403e7314c47b0c07fbc5e4ef21d939532 ("softirq, warning fix: correct a format to avoid a warning") fix correctly. The type of a pointer subtraction is not "int", nor is it "long". It can be either (or something else). It's "ptrdiff_t", and the printk format for it is "%td". Cc: Frederic Weisbecker Cc: Ingo Molnar Signed-off-by: Linus Torvalds --- kernel/softirq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/softirq.c') diff --git a/kernel/softirq.c b/kernel/softirq.c index be7a8292f99..37d67aa2d56 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -210,7 +210,7 @@ restart: h->action(h); if (unlikely(prev_count != preempt_count())) { - printk(KERN_ERR "huh, entered softirq %d %p" + printk(KERN_ERR "huh, entered softirq %td %p" "with preempt_count %08x," " exited with %08x?\n", h - softirq_vec, h->action, prev_count, preempt_count()); -- cgit v1.2.3-70-g09d2 From 54514a70adefe356afe854e2d3912d46668068e6 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Tue, 23 Sep 2008 22:15:57 -0700 Subject: softirq: Add support for triggering softirq work on softirqs. This is basically a genericization of Jens Axboe's block layer remote softirq changes. Signed-off-by: David S. Miller Signed-off-by: Jens Axboe --- include/linux/interrupt.h | 21 ++++++++ include/linux/smp.h | 4 +- kernel/softirq.c | 129 ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 153 insertions(+), 1 deletion(-) (limited to 'kernel/softirq.c') diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 54b3623434e..35a61dc60d5 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -11,6 +11,8 @@ #include #include #include +#include +#include #include #include #include @@ -273,6 +275,25 @@ extern void softirq_init(void); extern void raise_softirq_irqoff(unsigned int nr); extern void raise_softirq(unsigned int nr); +/* This is the worklist that queues up per-cpu softirq work. + * + * send_remote_sendirq() adds work to these lists, and + * the softirq handler itself dequeues from them. The queues + * are protected by disabling local cpu interrupts and they must + * only be accessed by the local cpu that they are for. + */ +DECLARE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); + +/* Try to send a softirq to a remote cpu. If this cannot be done, the + * work will be queued to the local cpu. + */ +extern void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq); + +/* Like send_remote_softirq(), but the caller must disable local cpu interrupts + * and compute the current cpu, passed in as 'this_cpu'. + */ +extern void __send_remote_softirq(struct call_single_data *cp, int cpu, + int this_cpu, int softirq); /* Tasklets --- multithreaded analogue of BHs. diff --git a/include/linux/smp.h b/include/linux/smp.h index 66484d4a845..2e4d58b26c0 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -7,6 +7,7 @@ */ #include +#include #include #include @@ -16,7 +17,8 @@ struct call_single_data { struct list_head list; void (*func) (void *info); void *info; - unsigned int flags; + u16 flags; + u16 priv; }; #ifdef CONFIG_SMP diff --git a/kernel/softirq.c b/kernel/softirq.c index 37d67aa2d56..83ba21a13bd 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -6,6 +6,8 @@ * Distribute under GPLv2. * * Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903) + * + * Remote softirq infrastructure is by Jens Axboe. */ #include @@ -474,17 +476,144 @@ void tasklet_kill(struct tasklet_struct *t) EXPORT_SYMBOL(tasklet_kill); +DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); +EXPORT_PER_CPU_SYMBOL(softirq_work_list); + +static void __local_trigger(struct call_single_data *cp, int softirq) +{ + struct list_head *head = &__get_cpu_var(softirq_work_list[softirq]); + + list_add_tail(&cp->list, head); + + /* Trigger the softirq only if the list was previously empty. */ + if (head->next == &cp->list) + raise_softirq_irqoff(softirq); +} + +#ifdef CONFIG_USE_GENERIC_SMP_HELPERS +static void remote_softirq_receive(void *data) +{ + struct call_single_data *cp = data; + unsigned long flags; + int softirq; + + softirq = cp->priv; + + local_irq_save(flags); + __local_trigger(cp, softirq); + local_irq_restore(flags); +} + +static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) +{ + if (cpu_online(cpu)) { + cp->func = remote_softirq_receive; + cp->info = cp; + cp->flags = 0; + cp->priv = softirq; + + __smp_call_function_single(cpu, cp); + return 0; + } + return 1; +} +#else /* CONFIG_USE_GENERIC_SMP_HELPERS */ +static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) +{ + return 1; +} +#endif + +/** + * __send_remote_softirq - try to schedule softirq work on a remote cpu + * @cp: private SMP call function data area + * @cpu: the remote cpu + * @this_cpu: the currently executing cpu + * @softirq: the softirq for the work + * + * Attempt to schedule softirq work on a remote cpu. If this cannot be + * done, the work is instead queued up on the local cpu. + * + * Interrupts must be disabled. + */ +void __send_remote_softirq(struct call_single_data *cp, int cpu, int this_cpu, int softirq) +{ + if (cpu == this_cpu || __try_remote_softirq(cp, cpu, softirq)) + __local_trigger(cp, softirq); +} +EXPORT_SYMBOL(__send_remote_softirq); + +/** + * send_remote_softirq - try to schedule softirq work on a remote cpu + * @cp: private SMP call function data area + * @cpu: the remote cpu + * @softirq: the softirq for the work + * + * Like __send_remote_softirq except that disabling interrupts and + * computing the current cpu is done for the caller. + */ +void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq) +{ + unsigned long flags; + int this_cpu; + + local_irq_save(flags); + this_cpu = smp_processor_id(); + __send_remote_softirq(cp, cpu, this_cpu, softirq); + local_irq_restore(flags); +} +EXPORT_SYMBOL(send_remote_softirq); + +static int __cpuinit remote_softirq_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) +{ + /* + * If a CPU goes away, splice its entries to the current CPU + * and trigger a run of the softirq + */ + if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { + int cpu = (unsigned long) hcpu; + int i; + + local_irq_disable(); + for (i = 0; i < NR_SOFTIRQS; i++) { + struct list_head *head = &per_cpu(softirq_work_list[i], cpu); + struct list_head *local_head; + + if (list_empty(head)) + continue; + + local_head = &__get_cpu_var(softirq_work_list[i]); + list_splice_init(head, local_head); + raise_softirq_irqoff(i); + } + local_irq_enable(); + } + + return NOTIFY_OK; +} + +static struct notifier_block __cpuinitdata remote_softirq_cpu_notifier = { + .notifier_call = remote_softirq_cpu_notify, +}; + void __init softirq_init(void) { int cpu; for_each_possible_cpu(cpu) { + int i; + per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head; per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head; + for (i = 0; i < NR_SOFTIRQS; i++) + INIT_LIST_HEAD(&per_cpu(softirq_work_list[i], cpu)); } + register_hotcpu_notifier(&remote_softirq_cpu_notifier); + open_softirq(TASKLET_SOFTIRQ, tasklet_action); open_softirq(HI_SOFTIRQ, tasklet_hi_action); } -- cgit v1.2.3-70-g09d2 From 719254faa17ffedc87ba0fadb9b34e535c9758d5 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 17 Oct 2008 09:59:47 +0200 Subject: NOHZ: unify the nohz function calls in irq_enter() We have two separate nohz function calls in irq_enter() for no good reason. Just call a single NOHZ function from irq_enter() and call the bits in the tick code. Signed-off-by: Thomas Gleixner --- include/linux/tick.h | 7 +++---- kernel/softirq.c | 10 +++------- kernel/time/tick-sched.c | 13 ++++++++++++- 3 files changed, 18 insertions(+), 12 deletions(-) (limited to 'kernel/softirq.c') diff --git a/include/linux/tick.h b/include/linux/tick.h index 98921a3e1aa..b6ec8189ac0 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -96,9 +96,11 @@ extern cpumask_t *tick_get_broadcast_oneshot_mask(void); extern void tick_clock_notify(void); extern int tick_check_oneshot_change(int allow_nohz); extern struct tick_sched *tick_get_tick_sched(int cpu); +extern void tick_check_idle(int cpu); # else static inline void tick_clock_notify(void) { } static inline int tick_check_oneshot_change(int allow_nohz) { return 0; } +static inline void tick_check_idle(int cpu) { } # endif #else /* CONFIG_GENERIC_CLOCKEVENTS */ @@ -106,26 +108,23 @@ static inline void tick_init(void) { } static inline void tick_cancel_sched_timer(int cpu) { } static inline void tick_clock_notify(void) { } static inline int tick_check_oneshot_change(int allow_nohz) { return 0; } +static inline void tick_check_idle(int cpu) { } #endif /* !CONFIG_GENERIC_CLOCKEVENTS */ # ifdef CONFIG_NO_HZ extern void tick_nohz_stop_sched_tick(int inidle); extern void tick_nohz_restart_sched_tick(void); -extern void tick_nohz_update_jiffies(void); extern ktime_t tick_nohz_get_sleep_length(void); -extern void tick_nohz_stop_idle(int cpu); extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time); # else static inline void tick_nohz_stop_sched_tick(int inidle) { } static inline void tick_nohz_restart_sched_tick(void) { } -static inline void tick_nohz_update_jiffies(void) { } static inline ktime_t tick_nohz_get_sleep_length(void) { ktime_t len = { .tv64 = NSEC_PER_SEC/HZ }; return len; } -static inline void tick_nohz_stop_idle(int cpu) { } static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; } # endif /* !NO_HZ */ diff --git a/kernel/softirq.c b/kernel/softirq.c index 37d67aa2d56..d410014279e 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -265,16 +265,12 @@ asmlinkage void do_softirq(void) */ void irq_enter(void) { -#ifdef CONFIG_NO_HZ int cpu = smp_processor_id(); + if (idle_cpu(cpu) && !in_interrupt()) - tick_nohz_stop_idle(cpu); -#endif + tick_check_idle(cpu); + __irq_enter(); -#ifdef CONFIG_NO_HZ - if (idle_cpu(cpu)) - tick_nohz_update_jiffies(); -#endif } #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index b711ffcb106..fdcf3f93bb8 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -155,7 +155,7 @@ void tick_nohz_update_jiffies(void) touch_softlockup_watchdog(); } -void tick_nohz_stop_idle(int cpu) +static void tick_nohz_stop_idle(int cpu) { struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); @@ -558,6 +558,17 @@ static inline void tick_nohz_switch_to_nohz(void) { } #endif /* NO_HZ */ +/* + * Called from irq_enter to notify about the possible interruption of idle() + */ +void tick_check_idle(int cpu) +{ +#ifdef CONFIG_NO_HZ + tick_nohz_stop_idle(cpu); + tick_nohz_update_jiffies(); +#endif +} + /* * High resolution timer specific code */ -- cgit v1.2.3-70-g09d2