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Date: Fri, 30 Jul 2010 11:57:45 +0200
From: Tomasz Buchert <tomasz.buchert@...ia.fr>
To: linux-kernel@...r.kernel.org,
Daniel Walker <dwalker@...eaurora.org>,
Stanislaw Gruszka <sgruszka@...hat.com>,
Peter Zijlstra <peterz@...radead.org>
Cc: Tomasz Buchert <tomasz.buchert@...ia.fr>
Subject: [PATCH 2/4] posix-cpu-timers: Introduction of wall clocks
Currently Linux lacks a good way to get an elapsed time
of a process/thread. This patch adds the interface to
obtain this piece of information. The access to the new
thread/process clock is restricted according to the same
rules as the access to the CPU clocks.
POSIX_CLOCK_WALL occupies previously unused value
(POSIX_CLOCK_MAX) in the clockid_t representation of a clock.
Signed-off-by: Tomasz Buchert <tomasz.buchert@...ia.fr>
---
include/linux/posix-timers.h | 27 ++++++
include/linux/time.h | 2 +
kernel/posix-cpu-timers.c | 214 +++++++++++++++++++++++++++++++++++++++---
kernel/posix-timers.c | 25 ++++-
4 files changed, 252 insertions(+), 16 deletions(-)
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index 07f33d2..d747870 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -28,12 +28,22 @@ struct cpu_timer_list {
#define POSIX_CLOCK_PROF 0
#define POSIX_CLOCK_VIRT 1
#define POSIX_CLOCK_SCHED 2
+#define POSIX_CLOCK_WALL 3
#define POSIX_CLOCK_MAX 3
+#define IS_CPU_CLOCK(clock) ((clock) < 0 && \
+ (POSIX_CLOCK_WHICH(clock) ^ POSIX_CLOCK_WALL))
+#define IS_WALL_CLOCK(clock) ((clock) < 0 && \
+ !(POSIX_CLOCK_WHICH(clock) ^ POSIX_CLOCK_WALL))
+
#define MAKE_PROCESS_CPUCLOCK(pid, clock) \
((~(clockid_t) (pid) << 3) | (clockid_t) (clock))
#define MAKE_THREAD_CPUCLOCK(tid, clock) \
MAKE_PROCESS_CPUCLOCK((tid), (clock) | POSIX_CLOCK_PERTHREAD_MASK)
+#define MAKE_PROCESS_WALLCLOCK(pid) \
+ MAKE_PROCESS_CPUCLOCK(pid, POSIX_CLOCK_WALL)
+#define MAKE_THREAD_WALLCLOCK(pid) \
+ MAKE_THREAD_CPUCLOCK(pid, POSIX_CLOCK_WALL)
/* POSIX.1b interval timer structure. */
struct k_itimer {
@@ -95,6 +105,8 @@ int do_posix_clock_nosettime(const clockid_t, struct timespec *tp);
/* function to call to trigger timer event */
int posix_timer_event(struct k_itimer *timr, int si_private);
+/* CPU clocks */
+
int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *ts);
int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *ts);
int posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *ts);
@@ -120,4 +132,19 @@ long clock_nanosleep_restart(struct restart_block *restart_block);
void update_rlimit_cpu(unsigned long rlim_new);
+/* Wall clocks */
+
+int wall_clock_getres(clockid_t which_clock, struct timespec *tp);
+int wall_clock_get(clockid_t which_clock, struct timespec *tp);
+int wall_clock_set(const clockid_t which_clock, struct timespec *tp);
+int wall_nsleep(const clockid_t which_clock, int flags,
+ struct timespec *tsave, struct timespec __user *rmtp);
+long wall_nsleep_restart(struct restart_block *restart_block);
+int wall_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting);
+int wall_timer_create(struct k_itimer *new_timer);
+int wall_timer_set(struct k_itimer *timr, int flags,
+ struct itimerspec *new_setting,
+ struct itimerspec *old_setting);
+int wall_timer_del(struct k_itimer *timer);
+
#endif
diff --git a/include/linux/time.h b/include/linux/time.h
index ea3559f..596e6fb 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -275,6 +275,8 @@ struct itimerval {
#define CLOCK_MONOTONIC_RAW 4
#define CLOCK_REALTIME_COARSE 5
#define CLOCK_MONOTONIC_COARSE 6
+#define CLOCK_PROCESS_WALLTIME_ID 7
+#define CLOCK_THREAD_WALLTIME_ID 8
/*
* The IDs of various hardware clocks:
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index f106ac6..78ad536 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -25,29 +25,201 @@ void update_rlimit_cpu(unsigned long rlim_new)
spin_unlock_irq(¤t->sighand->siglock);
}
-static int check_clock(const clockid_t which_clock)
+static int check_task_clock(const clockid_t which_clock)
{
int error = 0;
struct task_struct *p;
const pid_t pid = POSIX_CLOCK_PID(which_clock);
- if (POSIX_CLOCK_WHICH(which_clock) >= POSIX_CLOCK_MAX)
- return -EINVAL;
-
if (pid == 0)
return 0;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_task_by_vpid(pid);
if (!p || !(POSIX_CLOCK_PERTHREAD(which_clock) ?
same_thread_group(p, current) : thread_group_leader(p))) {
error = -EINVAL;
}
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return error;
}
+static inline int check_cpu_clock(const clockid_t which_clock)
+{
+ return !IS_CPU_CLOCK(which_clock) ?
+ -EINVAL : check_task_clock(which_clock);
+}
+
+static inline int check_wall_clock(const clockid_t which_clock)
+{
+ return !IS_WALL_CLOCK(which_clock) ?
+ -EINVAL : check_task_clock(which_clock);
+}
+
+/* Wall time clocks */
+
+/* Get the start time of the process/thread referenced by the wall clock.
+ * RCU lock required. */
+
+static int get_start_time(clockid_t which_clock, struct timespec *start)
+{
+ struct task_struct *p =
+ find_task_by_vpid(POSIX_CLOCK_PID(which_clock));
+ if (p && (
+ (POSIX_CLOCK_PERTHREAD(which_clock) &&
+ same_thread_group(p, current)) ||
+ (!POSIX_CLOCK_PERTHREAD(which_clock) &&
+ thread_group_leader(p) && p->sighand))) {
+ *start = p->start_time;
+ return 0;
+ }
+ return -EINVAL;
+}
+
+/* monotonic clock is used to get start_time and uptime
+ * so the precision is twice the precision of the monotonic clock */
+
+int wall_clock_getres(clockid_t which_clock, struct timespec *tp)
+{
+ int error = check_wall_clock(which_clock);
+ if (error)
+ return error;
+ error = hrtimer_get_res(CLOCK_MONOTONIC, tp);
+ if (error)
+ return error;
+ *tp = timespec_add_safe(*tp, *tp);
+ return 0;
+}
+
+int wall_clock_get(clockid_t which_clock, struct timespec *tp)
+{
+ struct timespec uptime, start;
+ int error = -EINVAL;
+
+ if (!IS_WALL_CLOCK(which_clock))
+ return error;
+
+ if (POSIX_CLOCK_PID(which_clock) == 0) {
+ start = (POSIX_CLOCK_PERTHREAD(which_clock) ?
+ current : current->group_leader)->start_time;
+ error = 0;
+ } else {
+ rcu_read_lock();
+ error = get_start_time(which_clock, &start);
+ rcu_read_unlock();
+ }
+
+ if (error)
+ return error;
+
+ do_posix_clock_monotonic_gettime(&uptime);
+ *tp = timespec_sub(uptime, start);
+
+ return 0;
+}
+
+int wall_clock_set(const clockid_t which_clock,
+ struct timespec *tp)
+{
+ return check_wall_clock(which_clock) ?: -EPERM;
+}
+
+int wall_nsleep(const clockid_t which_clock, int flags,
+ struct timespec *tsave, struct timespec __user *rmtp)
+{
+ if (!IS_WALL_CLOCK(which_clock))
+ return -EINVAL;
+
+ if (flags & TIMER_ABSTIME) {
+ int error;
+ struct timespec start;
+
+ rcu_read_lock();
+ error = get_start_time(which_clock, &start);
+ rcu_read_unlock();
+
+ if (error)
+ return error;
+ *tsave = timespec_add_safe(*tsave, start);
+ }
+ return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
+ HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
+ CLOCK_MONOTONIC);
+}
+
+long wall_nsleep_restart(struct restart_block *restart_block)
+{
+ return -EINVAL;
+}
+
+int wall_timer_get(struct k_itimer *timr,
+ struct itimerspec *cur_setting)
+{
+ return -EINVAL;
+}
+
+int wall_timer_create(struct k_itimer *new_timer)
+{
+ return -EINVAL;
+}
+
+int wall_timer_set(struct k_itimer *timr, int flags,
+ struct itimerspec *new_setting,
+ struct itimerspec *old_setting)
+{
+ return -EINVAL;
+}
+
+int wall_timer_del(struct k_itimer *timer)
+{
+ return -EINVAL;
+}
+
+#define PROCESS_WALLCLOCK MAKE_PROCESS_WALLCLOCK(0)
+#define THREAD_WALLCLOCK MAKE_THREAD_WALLCLOCK(0)
+
+static int process_wall_getres(const clockid_t which_clock,
+ struct timespec *tp)
+{
+ return wall_clock_getres(PROCESS_WALLCLOCK, tp);
+}
+static int process_wall_get(const clockid_t which_clock, struct timespec *tp)
+{
+ return wall_clock_get(PROCESS_WALLCLOCK, tp);
+}
+static int process_wall_nsleep(const clockid_t which_clock, int flags,
+ struct timespec *rqtp,
+ struct timespec __user *rmtp)
+{
+ return wall_nsleep(PROCESS_WALLCLOCK, flags, rqtp, rmtp);
+}
+static long process_wall_nsleep_restart(struct restart_block *restart_block)
+{
+ return -EINVAL;
+}
+static int thread_wall_getres(const clockid_t which_clock,
+ struct timespec *tp)
+{
+ return wall_clock_getres(THREAD_WALLCLOCK, tp);
+}
+static int thread_wall_get(const clockid_t which_clock, struct timespec *tp)
+{
+ return wall_clock_get(THREAD_WALLCLOCK, tp);
+}
+static int thread_wall_nsleep(const clockid_t which_clock, int flags,
+ struct timespec *rqtp,
+ struct timespec __user *rmtp)
+{
+ return wall_nsleep(THREAD_WALLCLOCK, flags, rqtp, rmtp);
+}
+static long thread_wall_nsleep_restart(struct restart_block *restart_block)
+{
+ return -EINVAL;
+}
+
+/* CPU time clocks */
+
static inline union cpu_time_count
timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
{
@@ -178,7 +350,7 @@ static inline cputime_t virt_ticks(struct task_struct *p)
int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
{
- int error = check_clock(which_clock);
+ int error = check_cpu_clock(which_clock);
if (!error) {
tp->tv_sec = 0;
tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
@@ -200,7 +372,7 @@ int posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
* You can never reset a CPU clock, but we check for other errors
* in the call before failing with EPERM.
*/
- int error = check_clock(which_clock);
+ int error = check_cpu_clock(which_clock);
if (error == 0) {
error = -EPERM;
}
@@ -1612,7 +1784,7 @@ static long thread_cpu_nsleep_restart(struct restart_block *restart_block)
static __init int init_posix_cpu_timers(void)
{
- struct k_clock process = {
+ struct k_clock cpu_process = {
.clock_getres = process_cpu_clock_getres,
.clock_get = process_cpu_clock_get,
.clock_set = do_posix_clock_nosettime,
@@ -1620,7 +1792,7 @@ static __init int init_posix_cpu_timers(void)
.nsleep = process_cpu_nsleep,
.nsleep_restart = process_cpu_nsleep_restart,
};
- struct k_clock thread = {
+ struct k_clock cpu_thread = {
.clock_getres = thread_cpu_clock_getres,
.clock_get = thread_cpu_clock_get,
.clock_set = do_posix_clock_nosettime,
@@ -1628,10 +1800,28 @@ static __init int init_posix_cpu_timers(void)
.nsleep = thread_cpu_nsleep,
.nsleep_restart = thread_cpu_nsleep_restart,
};
+ struct k_clock wall_process = {
+ .clock_getres = process_wall_getres,
+ .clock_get = process_wall_get,
+ .clock_set = wall_clock_set,
+ .timer_create = wall_timer_create,
+ .nsleep = process_wall_nsleep,
+ .nsleep_restart = process_wall_nsleep_restart,
+ };
+ struct k_clock wall_thread = {
+ .clock_getres = thread_wall_getres,
+ .clock_get = thread_wall_get,
+ .clock_set = wall_clock_set,
+ .timer_create = wall_timer_create,
+ .nsleep = thread_wall_nsleep,
+ .nsleep_restart = thread_wall_nsleep_restart,
+ };
struct timespec ts;
- register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
- register_posix_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
+ register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &cpu_process);
+ register_posix_clock(CLOCK_THREAD_CPUTIME_ID, &cpu_thread);
+ register_posix_clock(CLOCK_PROCESS_WALLTIME_ID, &wall_process);
+ register_posix_clock(CLOCK_THREAD_WALLTIME_ID, &wall_thread);
cputime_to_timespec(cputime_one_jiffy, &ts);
onecputick = ts.tv_nsec;
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index ad72342..beaef9e 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -153,12 +153,29 @@ static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
}
/*
+ * Call either POSIX CPU clocks or wall clocks.
+ */
+
+#define CLOCK_DISPATCH_PERTASK(clock, call, arglist) \
+ (IS_CPU_CLOCK(clock) ? \
+ posix_cpu_##call arglist : wall_##call arglist)
+
+/*
* Call the k_clock hook function if non-null, or the default function.
*/
+
+#define CLOCK_DISPATCH_NORMAL(clock, call, arglist) \
+ (posix_clocks[clock].call != NULL ? \
+ (*posix_clocks[clock].call) arglist : common_##call arglist)
+
+/*
+ * Dispatch between thread/process clocks and global clocks.
+ */
+
#define CLOCK_DISPATCH(clock, call, arglist) \
- ((clock) < 0 ? posix_cpu_##call arglist : \
- (posix_clocks[clock].call != NULL \
- ? (*posix_clocks[clock].call) arglist : common_##call arglist))
+ ((clock) < 0 ? \
+ CLOCK_DISPATCH_PERTASK((clock), call, arglist) : \
+ CLOCK_DISPATCH_NORMAL((clock), call, arglist))
/*
* Default clock hook functions when the struct k_clock passed
@@ -213,7 +230,7 @@ static int no_nsleep(const clockid_t which_clock, int flags,
*/
static inline int invalid_clockid(const clockid_t which_clock)
{
- if (which_clock < 0) /* CPU clock, posix_cpu_* will check it */
+ if (which_clock < 0) /* per task clock, checked later */
return 0;
if ((unsigned) which_clock >= MAX_CLOCKS)
return 1;
--
1.6.3.3
--
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