From abb74cefa9c682fb38ba86c17ca3c86fed6cc464 Mon Sep 17 00:00:00 2001 From: Venkatesh Pallipadi Date: Tue, 21 Dec 2010 17:09:03 -0800 Subject: [PATCH] sched: Export ns irqtimes through /proc/stat CONFIG_IRQ_TIME_ACCOUNTING adds ns granularity irq time on each CPU. This info is already used in scheduler to do proper task chargeback (earlier patches). This patch retro-fits this ns granularity hardirq and softirq information to /proc/stat irq and softirq fields. The update is still done on timer tick, where we look at accumulated ns hardirq/softirq time and account the tick to user/system/irq/hardirq/guest accordingly. No new interface added. Earlier versions looked at adding this as new fields in some /proc files. This one seems to be the best in terms of impact to existing apps, even though it has somewhat more kernel code than earlier versions. Tested-by: Shaun Ruffell Signed-off-by: Venkatesh Pallipadi Signed-off-by: Peter Zijlstra LKML-Reference: <1292980144-28796-5-git-send-email-venki@google.com> Signed-off-by: Ingo Molnar --- kernel/sched.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 102 insertions(+) diff --git a/kernel/sched.c b/kernel/sched.c index e3fa92106ed7..2a3c9799d76b 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1920,8 +1920,40 @@ static void update_rq_clock_task(struct rq *rq, s64 delta) sched_rt_avg_update(rq, irq_delta); } +static int irqtime_account_hi_update(void) +{ + struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; + unsigned long flags; + u64 latest_ns; + int ret = 0; + + local_irq_save(flags); + latest_ns = this_cpu_read(cpu_hardirq_time); + if (cputime64_gt(nsecs_to_cputime64(latest_ns), cpustat->irq)) + ret = 1; + local_irq_restore(flags); + return ret; +} + +static int irqtime_account_si_update(void) +{ + struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; + unsigned long flags; + u64 latest_ns; + int ret = 0; + + local_irq_save(flags); + latest_ns = this_cpu_read(cpu_softirq_time); + if (cputime64_gt(nsecs_to_cputime64(latest_ns), cpustat->softirq)) + ret = 1; + local_irq_restore(flags); + return ret; +} + #else /* CONFIG_IRQ_TIME_ACCOUNTING */ +#define sched_clock_irqtime (0) + static void update_rq_clock_task(struct rq *rq, s64 delta) { rq->clock_task += delta; @@ -3621,6 +3653,65 @@ void account_system_time(struct task_struct *p, int hardirq_offset, __account_system_time(p, cputime, cputime_scaled, target_cputime64); } +#ifdef CONFIG_IRQ_TIME_ACCOUNTING +/* + * Account a tick to a process and cpustat + * @p: the process that the cpu time gets accounted to + * @user_tick: is the tick from userspace + * @rq: the pointer to rq + * + * Tick demultiplexing follows the order + * - pending hardirq update + * - pending softirq update + * - user_time + * - idle_time + * - system time + * - check for guest_time + * - else account as system_time + * + * Check for hardirq is done both for system and user time as there is + * no timer going off while we are on hardirq and hence we may never get an + * opportunity to update it solely in system time. + * p->stime and friends are only updated on system time and not on irq + * softirq as those do not count in task exec_runtime any more. + */ +static void irqtime_account_process_tick(struct task_struct *p, int user_tick, + struct rq *rq) +{ + cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy); + cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy); + struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; + + if (irqtime_account_hi_update()) { + cpustat->irq = cputime64_add(cpustat->irq, tmp); + } else if (irqtime_account_si_update()) { + cpustat->softirq = cputime64_add(cpustat->softirq, tmp); + } else if (user_tick) { + account_user_time(p, cputime_one_jiffy, one_jiffy_scaled); + } else if (p == rq->idle) { + account_idle_time(cputime_one_jiffy); + } else if (p->flags & PF_VCPU) { /* System time or guest time */ + account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled); + } else { + __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled, + &cpustat->system); + } +} + +static void irqtime_account_idle_ticks(int ticks) +{ + int i; + struct rq *rq = this_rq(); + + for (i = 0; i < ticks; i++) + irqtime_account_process_tick(current, 0, rq); +} +#else +static void irqtime_account_idle_ticks(int ticks) {} +static void irqtime_account_process_tick(struct task_struct *p, int user_tick, + struct rq *rq) {} +#endif + /* * Account for involuntary wait time. * @steal: the cpu time spent in involuntary wait @@ -3661,6 +3752,11 @@ void account_process_tick(struct task_struct *p, int user_tick) cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy); struct rq *rq = this_rq(); + if (sched_clock_irqtime) { + irqtime_account_process_tick(p, user_tick, rq); + return; + } + if (user_tick) account_user_time(p, cputime_one_jiffy, one_jiffy_scaled); else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET)) @@ -3686,6 +3782,12 @@ void account_steal_ticks(unsigned long ticks) */ void account_idle_ticks(unsigned long ticks) { + + if (sched_clock_irqtime) { + irqtime_account_idle_ticks(ticks); + return; + } + account_idle_time(jiffies_to_cputime(ticks)); } -- 2.20.1