From 2ff678b8da6478d861c1b0ecb3ac14575760e906 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 9 Jan 2006 20:52:34 -0800 Subject: [PATCH] [PATCH] hrtimer: switch itimers to hrtimer switch itimers to a hrtimers-based implementation Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/exec.c | 6 +-- fs/proc/array.c | 6 +-- include/linux/sched.h | 5 +- include/linux/timer.h | 2 +- kernel/exit.c | 2 +- kernel/fork.c | 6 +-- kernel/itimer.c | 106 ++++++++++++++++++++---------------------- 7 files changed, 65 insertions(+), 68 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index fd02ea4a81e..b5bcf1aae0a 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -632,10 +632,10 @@ static inline int de_thread(struct task_struct *tsk) * synchronize with any firing (by calling del_timer_sync) * before we can safely let the old group leader die. */ - sig->real_timer.data = (unsigned long)current; + sig->real_timer.data = current; spin_unlock_irq(lock); - if (del_timer_sync(&sig->real_timer)) - add_timer(&sig->real_timer); + if (hrtimer_cancel(&sig->real_timer)) + hrtimer_restart(&sig->real_timer); spin_lock_irq(lock); } while (atomic_read(&sig->count) > count) { diff --git a/fs/proc/array.c b/fs/proc/array.c index 5e9251f6531..7eb1bd7f800 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -330,7 +330,7 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole) unsigned long min_flt = 0, maj_flt = 0; cputime_t cutime, cstime, utime, stime; unsigned long rsslim = 0; - unsigned long it_real_value = 0; + DEFINE_KTIME(it_real_value); struct task_struct *t; char tcomm[sizeof(task->comm)]; @@ -386,7 +386,7 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole) utime = cputime_add(utime, task->signal->utime); stime = cputime_add(stime, task->signal->stime); } - it_real_value = task->signal->it_real_value; + it_real_value = task->signal->real_timer.expires; } ppid = pid_alive(task) ? task->group_leader->real_parent->tgid : 0; read_unlock(&tasklist_lock); @@ -435,7 +435,7 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole) priority, nice, num_threads, - jiffies_to_clock_t(it_real_value), + (long) ktime_to_clock_t(it_real_value), start_time, vsize, mm ? get_mm_rss(mm) : 0, diff --git a/include/linux/sched.h b/include/linux/sched.h index 85b53f87c70..ee4677ad204 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -105,6 +105,7 @@ extern unsigned long nr_iowait(void); #include #include #include +#include #include @@ -398,8 +399,8 @@ struct signal_struct { struct list_head posix_timers; /* ITIMER_REAL timer for the process */ - struct timer_list real_timer; - unsigned long it_real_value, it_real_incr; + struct hrtimer real_timer; + ktime_t it_real_incr; /* ITIMER_PROF and ITIMER_VIRTUAL timers for the process */ cputime_t it_prof_expires, it_virt_expires; diff --git a/include/linux/timer.h b/include/linux/timer.h index 72f3a778110..9b9877fd250 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -96,6 +96,6 @@ static inline void add_timer(struct timer_list *timer) extern void init_timers(void); extern void run_local_timers(void); -extern void it_real_fn(unsigned long); +extern int it_real_fn(void *); #endif diff --git a/kernel/exit.c b/kernel/exit.c index 309a46fa16f..e75a51f3376 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -842,7 +842,7 @@ fastcall NORET_TYPE void do_exit(long code) } group_dead = atomic_dec_and_test(&tsk->signal->live); if (group_dead) { - del_timer_sync(&tsk->signal->real_timer); + hrtimer_cancel(&tsk->signal->real_timer); exit_itimers(tsk->signal); acct_process(code); } diff --git a/kernel/fork.c b/kernel/fork.c index b18d64554fe..3bdcab49998 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -801,10 +801,10 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts init_sigpending(&sig->shared_pending); INIT_LIST_HEAD(&sig->posix_timers); - sig->it_real_value = sig->it_real_incr = 0; + hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC); + sig->it_real_incr.tv64 = 0; sig->real_timer.function = it_real_fn; - sig->real_timer.data = (unsigned long) tsk; - init_timer(&sig->real_timer); + sig->real_timer.data = tsk; sig->it_virt_expires = cputime_zero; sig->it_virt_incr = cputime_zero; diff --git a/kernel/itimer.c b/kernel/itimer.c index 7c1b25e25e4..c2c05c4ff28 100644 --- a/kernel/itimer.c +++ b/kernel/itimer.c @@ -12,36 +12,46 @@ #include #include #include +#include #include -static unsigned long it_real_value(struct signal_struct *sig) +/** + * itimer_get_remtime - get remaining time for the timer + * + * @timer: the timer to read + * + * Returns the delta between the expiry time and now, which can be + * less than zero or 1usec for an pending expired timer + */ +static struct timeval itimer_get_remtime(struct hrtimer *timer) { - unsigned long val = 0; - if (timer_pending(&sig->real_timer)) { - val = sig->real_timer.expires - jiffies; + ktime_t rem = hrtimer_get_remaining(timer); - /* look out for negative/zero itimer.. */ - if ((long) val <= 0) - val = 1; - } - return val; + /* + * Racy but safe: if the itimer expires after the above + * hrtimer_get_remtime() call but before this condition + * then we return 0 - which is correct. + */ + if (hrtimer_active(timer)) { + if (rem.tv64 <= 0) + rem.tv64 = NSEC_PER_USEC; + } else + rem.tv64 = 0; + + return ktime_to_timeval(rem); } int do_getitimer(int which, struct itimerval *value) { struct task_struct *tsk = current; - unsigned long interval, val; cputime_t cinterval, cval; switch (which) { case ITIMER_REAL: - spin_lock_irq(&tsk->sighand->siglock); - interval = tsk->signal->it_real_incr; - val = it_real_value(tsk->signal); - spin_unlock_irq(&tsk->sighand->siglock); - jiffies_to_timeval(val, &value->it_value); - jiffies_to_timeval(interval, &value->it_interval); + value->it_value = itimer_get_remtime(&tsk->signal->real_timer); + value->it_interval = + ktime_to_timeval(tsk->signal->it_real_incr); break; case ITIMER_VIRTUAL: read_lock(&tasklist_lock); @@ -113,59 +123,45 @@ asmlinkage long sys_getitimer(int which, struct itimerval __user *value) } -void it_real_fn(unsigned long __data) +/* + * The timer is automagically restarted, when interval != 0 + */ +int it_real_fn(void *data) { - struct task_struct * p = (struct task_struct *) __data; - unsigned long inc = p->signal->it_real_incr; + struct task_struct *tsk = (struct task_struct *) data; - send_group_sig_info(SIGALRM, SEND_SIG_PRIV, p); + send_group_sig_info(SIGALRM, SEND_SIG_PRIV, tsk); - /* - * Now restart the timer if necessary. We don't need any locking - * here because do_setitimer makes sure we have finished running - * before it touches anything. - * Note, we KNOW we are (or should be) at a jiffie edge here so - * we don't need the +1 stuff. Also, we want to use the prior - * expire value so as to not "slip" a jiffie if we are late. - * Deal with requesting a time prior to "now" here rather than - * in add_timer. - */ - if (!inc) - return; - while (time_before_eq(p->signal->real_timer.expires, jiffies)) - p->signal->real_timer.expires += inc; - add_timer(&p->signal->real_timer); + if (tsk->signal->it_real_incr.tv64 != 0) { + hrtimer_forward(&tsk->signal->real_timer, + tsk->signal->it_real_incr); + + return HRTIMER_RESTART; + } + return HRTIMER_NORESTART; } int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue) { struct task_struct *tsk = current; - unsigned long val, interval, expires; + struct hrtimer *timer; + ktime_t expires; cputime_t cval, cinterval, nval, ninterval; switch (which) { case ITIMER_REAL: -again: - spin_lock_irq(&tsk->sighand->siglock); - interval = tsk->signal->it_real_incr; - val = it_real_value(tsk->signal); - /* We are sharing ->siglock with it_real_fn() */ - if (try_to_del_timer_sync(&tsk->signal->real_timer) < 0) { - spin_unlock_irq(&tsk->sighand->siglock); - goto again; - } - tsk->signal->it_real_incr = - timeval_to_jiffies(&value->it_interval); - expires = timeval_to_jiffies(&value->it_value); - if (expires) - mod_timer(&tsk->signal->real_timer, - jiffies + 1 + expires); - spin_unlock_irq(&tsk->sighand->siglock); + timer = &tsk->signal->real_timer; + hrtimer_cancel(timer); if (ovalue) { - jiffies_to_timeval(val, &ovalue->it_value); - jiffies_to_timeval(interval, - &ovalue->it_interval); + ovalue->it_value = itimer_get_remtime(timer); + ovalue->it_interval + = ktime_to_timeval(tsk->signal->it_real_incr); } + tsk->signal->it_real_incr = + timeval_to_ktime(value->it_interval); + expires = timeval_to_ktime(value->it_value); + if (expires.tv64 != 0) + hrtimer_start(timer, expires, HRTIMER_REL); break; case ITIMER_VIRTUAL: nval = timeval_to_cputime(&value->it_value); -- 2.41.1