[PATCH] hrtimer: switch itimers to hrtimer

switch itimers to a hrtimers-based implementation Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] hrtimer: switch itimers to hrtimer
switch itimers to a hrtimers-based implementation Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Thomas Gleixner · Linus Torvalds
1 parent df78488de7
Showing 7 changed files with 65 additions and 68 deletions Side-by-side Diff
fs/exec.c
fs/proc/array.c
include/linux/sched.h
include/linux/timer.h
kernel/exit.c
kernel/fork.c
kernel/itimer.c
@@ -632,10 +632,10 @@
 		 * 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) {
@@ -330,7 +330,7 @@
 	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 @@
 			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 @@
 		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,
@@ -105,6 +105,7 @@
 #include <linux/param.h>
 #include <linux/resource.h>
 #include <linux/timer.h>
+#include <linux/hrtimer.h>
  
 #include <asm/processor.h>
  
@@ -398,8 +399,8 @@
 	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;
@@ -96,7 +96,7 @@
  
 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
@@ -842,7 +842,7 @@
 	}
 	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);
 	}
@@ -801,10 +801,10 @@
 	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;
@@ -12,36 +12,46 @@
 #include <linux/syscalls.h>
 #include <linux/time.h>
 #include <linux/posix-timers.h>
+#include <linux/hrtimer.h>
  
 #include <asm/uaccess.h>
  
-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 @@
 }
  
  
-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);
...	...	@@ -632,10 +632,10 @@
632	632	* synchronize with any firing (by calling del_timer_sync)
633	633	* before we can safely let the old group leader die.
634	634	*/
635		- sig->real_timer.data = (unsigned long)current;
	635	+ sig->real_timer.data = current;
636	636	spin_unlock_irq(lock);
637		- if (del_timer_sync(&sig->real_timer))
638		- add_timer(&sig->real_timer);
	637	+ if (hrtimer_cancel(&sig->real_timer))
	638	+ hrtimer_restart(&sig->real_timer);
639	639	spin_lock_irq(lock);
640	640	}
641	641	while (atomic_read(&sig->count) > count) {
...	...	@@ -330,7 +330,7 @@
330	330	unsigned long min_flt = 0, maj_flt = 0;
331	331	cputime_t cutime, cstime, utime, stime;
332	332	unsigned long rsslim = 0;
333		- unsigned long it_real_value = 0;
	333	+ DEFINE_KTIME(it_real_value);
334	334	struct task_struct *t;
335	335	char tcomm[sizeof(task->comm)];
336	336
...	...	@@ -386,7 +386,7 @@
386	386	utime = cputime_add(utime, task->signal->utime);
387	387	stime = cputime_add(stime, task->signal->stime);
388	388	}
389		- it_real_value = task->signal->it_real_value;
	389	+ it_real_value = task->signal->real_timer.expires;
390	390	}
391	391	ppid = pid_alive(task) ? task->group_leader->real_parent->tgid : 0;
392	392	read_unlock(&tasklist_lock);
...	...	@@ -435,7 +435,7 @@
435	435	priority,
436	436	nice,
437	437	num_threads,
438		- jiffies_to_clock_t(it_real_value),
	438	+ (long) ktime_to_clock_t(it_real_value),
439	439	start_time,
440	440	vsize,
441	441	mm ? get_mm_rss(mm) : 0,
...	...	@@ -105,6 +105,7 @@
105	105	#include <linux/param.h>
106	106	#include <linux/resource.h>
107	107	#include <linux/timer.h>
	108	+#include <linux/hrtimer.h>
108	109
109	110	#include <asm/processor.h>
110	111
...	...	@@ -398,8 +399,8 @@
398	399	struct list_head posix_timers;
399	400
400	401	/* ITIMER_REAL timer for the process */
401		- struct timer_list real_timer;
402		- unsigned long it_real_value, it_real_incr;
	402	+ struct hrtimer real_timer;
	403	+ ktime_t it_real_incr;
403	404
404	405	/* ITIMER_PROF and ITIMER_VIRTUAL timers for the process */
405	406	cputime_t it_prof_expires, it_virt_expires;
...	...	@@ -96,7 +96,7 @@
96	96
97	97	extern void init_timers(void);
98	98	extern void run_local_timers(void);
99		-extern void it_real_fn(unsigned long);
	99	+extern int it_real_fn(void *);
100	100
101	101	#endif
...	...	@@ -842,7 +842,7 @@
842	842	}
843	843	group_dead = atomic_dec_and_test(&tsk->signal->live);
844	844	if (group_dead) {
845		- del_timer_sync(&tsk->signal->real_timer);
	845	+ hrtimer_cancel(&tsk->signal->real_timer);
846	846	exit_itimers(tsk->signal);
847	847	acct_process(code);
848	848	}
...	...	@@ -801,10 +801,10 @@
801	801	init_sigpending(&sig->shared_pending);
802	802	INIT_LIST_HEAD(&sig->posix_timers);
803	803
804		- sig->it_real_value = sig->it_real_incr = 0;
	804	+ hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC);
	805	+ sig->it_real_incr.tv64 = 0;
805	806	sig->real_timer.function = it_real_fn;
806		- sig->real_timer.data = (unsigned long) tsk;
807		- init_timer(&sig->real_timer);
	807	+ sig->real_timer.data = tsk;
808	808
809	809	sig->it_virt_expires = cputime_zero;
810	810	sig->it_virt_incr = cputime_zero;
...	...	@@ -12,36 +12,46 @@
12	12	#include <linux/syscalls.h>
13	13	#include <linux/time.h>
14	14	#include <linux/posix-timers.h>
	15	+#include <linux/hrtimer.h>
15	16
16	17	#include <asm/uaccess.h>
17	18
18		-static unsigned long it_real_value(struct signal_struct *sig)
	19	+/**
	20	+ * itimer_get_remtime - get remaining time for the timer
	21	+ *
	22	+ * @timer: the timer to read
	23	+ *
	24	+ * Returns the delta between the expiry time and now, which can be
	25	+ * less than zero or 1usec for an pending expired timer
	26	+ */
	27	+static struct timeval itimer_get_remtime(struct hrtimer *timer)
19	28	{
20		- unsigned long val = 0;
21		- if (timer_pending(&sig->real_timer)) {
22		- val = sig->real_timer.expires - jiffies;
	29	+ ktime_t rem = hrtimer_get_remaining(timer);
23	30
24		- /* look out for negative/zero itimer.. */
25		- if ((long) val <= 0)
26		- val = 1;
27		- }
28		- return val;
	31	+ /*
	32	+ * Racy but safe: if the itimer expires after the above
	33	+ * hrtimer_get_remtime() call but before this condition
	34	+ * then we return 0 - which is correct.
	35	+ */
	36	+ if (hrtimer_active(timer)) {
	37	+ if (rem.tv64 <= 0)
	38	+ rem.tv64 = NSEC_PER_USEC;
	39	+ } else
	40	+ rem.tv64 = 0;
	41	+
	42	+ return ktime_to_timeval(rem);
29	43	}
30	44
31	45	int do_getitimer(int which, struct itimerval *value)
32	46	{
33	47	struct task_struct *tsk = current;
34		- unsigned long interval, val;
35	48	cputime_t cinterval, cval;
36	49
37	50	switch (which) {
38	51	case ITIMER_REAL:
39		- spin_lock_irq(&tsk->sighand->siglock);
40		- interval = tsk->signal->it_real_incr;
41		- val = it_real_value(tsk->signal);
42		- spin_unlock_irq(&tsk->sighand->siglock);
43		- jiffies_to_timeval(val, &value->it_value);
44		- jiffies_to_timeval(interval, &value->it_interval);
	52	+ value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
	53	+ value->it_interval =
	54	+ ktime_to_timeval(tsk->signal->it_real_incr);
45	55	break;
46	56	case ITIMER_VIRTUAL:
47	57	read_lock(&tasklist_lock);
48	58
49	59
50	60
51	61
52	62
53	63
54	64
...	...	@@ -113,59 +123,45 @@
113	123	}
114	124
115	125
116		-void it_real_fn(unsigned long __data)
	126	+/*
	127	+ * The timer is automagically restarted, when interval != 0
	128	+ */
	129	+int it_real_fn(void *data)
117	130	{
118		- struct task_struct * p = (struct task_struct *) __data;
119		- unsigned long inc = p->signal->it_real_incr;
	131	+ struct task_struct tsk = (struct task_struct ) data;
120	132
121		- send_group_sig_info(SIGALRM, SEND_SIG_PRIV, p);
	133	+ send_group_sig_info(SIGALRM, SEND_SIG_PRIV, tsk);
122	134
123		- /*
124		- * Now restart the timer if necessary. We don't need any locking
125		- * here because do_setitimer makes sure we have finished running
126		- * before it touches anything.
127		- * Note, we KNOW we are (or should be) at a jiffie edge here so
128		- * we don't need the +1 stuff. Also, we want to use the prior
129		- * expire value so as to not "slip" a jiffie if we are late.
130		- * Deal with requesting a time prior to "now" here rather than
131		- * in add_timer.
132		- */
133		- if (!inc)
134		- return;
135		- while (time_before_eq(p->signal->real_timer.expires, jiffies))
136		- p->signal->real_timer.expires += inc;
137		- add_timer(&p->signal->real_timer);
	135	+ if (tsk->signal->it_real_incr.tv64 != 0) {
	136	+ hrtimer_forward(&tsk->signal->real_timer,
	137	+ tsk->signal->it_real_incr);
	138	+
	139	+ return HRTIMER_RESTART;
	140	+ }
	141	+ return HRTIMER_NORESTART;
138	142	}
139	143
140	144	int do_setitimer(int which, struct itimerval value, struct itimerval ovalue)
141	145	{
142	146	struct task_struct *tsk = current;
143		- unsigned long val, interval, expires;
	147	+ struct hrtimer *timer;
	148	+ ktime_t expires;
144	149	cputime_t cval, cinterval, nval, ninterval;
145	150
146	151	switch (which) {
147	152	case ITIMER_REAL:
148		-again:
149		- spin_lock_irq(&tsk->sighand->siglock);
150		- interval = tsk->signal->it_real_incr;
151		- val = it_real_value(tsk->signal);
152		- /* We are sharing ->siglock with it_real_fn() */
153		- if (try_to_del_timer_sync(&tsk->signal->real_timer) < 0) {
154		- spin_unlock_irq(&tsk->sighand->siglock);
155		- goto again;
156		- }
157		- tsk->signal->it_real_incr =
158		- timeval_to_jiffies(&value->it_interval);
159		- expires = timeval_to_jiffies(&value->it_value);
160		- if (expires)
161		- mod_timer(&tsk->signal->real_timer,
162		- jiffies + 1 + expires);
163		- spin_unlock_irq(&tsk->sighand->siglock);
	153	+ timer = &tsk->signal->real_timer;
	154	+ hrtimer_cancel(timer);
164	155	if (ovalue) {
165		- jiffies_to_timeval(val, &ovalue->it_value);
166		- jiffies_to_timeval(interval,
167		- &ovalue->it_interval);
	156	+ ovalue->it_value = itimer_get_remtime(timer);
	157	+ ovalue->it_interval
	158	+ = ktime_to_timeval(tsk->signal->it_real_incr);
168	159	}
	160	+ tsk->signal->it_real_incr =
	161	+ timeval_to_ktime(value->it_interval);
	162	+ expires = timeval_to_ktime(value->it_value);
	163	+ if (expires.tv64 != 0)
	164	+ hrtimer_start(timer, expires, HRTIMER_REL);
169	165	break;
170	166	case ITIMER_VIRTUAL:
171	167	nval = timeval_to_cputime(&value->it_value);