* [GIT PULL][PATCH 0/3] Timekeeping items for 4.11
@ 2017-01-28 0:59 John Stultz
2017-01-28 0:59 ` [PATCH 1/3] timekeeping: Remove unused timekeeping_{get,set}_tai_offset() John Stultz
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: John Stultz @ 2017-01-28 0:59 UTC (permalink / raw)
To: lkml
Cc: John Stultz, Thomas Gleixner, Richard Cochran, Prarit Bhargava,
Ingo Molnar
Hey Thomas, Ingo,
Just a few items I have queued for 4.11.
Let me know if you have any objections
thanks
-john
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
The following changes since commit 0c744ea4f77d72b3dcebb7a8f2684633ec79be88:
Linux 4.10-rc2 (2017-01-01 14:31:53 -0800)
are available in the git repository at:
https://git.linaro.org/people/john.stultz/linux.git fortglx/4.11/time
for you to fetch changes up to b18b6a9cef7f30e9a8b7738d5fc8d568cf660855:
timers: Omit POSIX timer stuff from task_struct when disabled (2017-01-27 13:05:26 -0800)
----------------------------------------------------------------
Nicolas Pitre (1):
timers: Omit POSIX timer stuff from task_struct when disabled
Russell King (1):
delay: Add explanation of udelay() inaccuracy
Stephen Boyd (1):
timekeeping: Remove unused timekeeping_{get,set}_tai_offset()
fs/proc/base.c | 4 ++--
include/linux/delay.h | 11 +++++++++++
include/linux/init_task.h | 40 +++++++++++++++++++++++++---------------
include/linux/sched.h | 13 ++++++++++---
kernel/fork.c | 10 +++++++++-
kernel/sched/rt.c | 4 ++++
kernel/sched/stats.h | 32 ++++++++++++++++++++------------
kernel/time/timekeeping.c | 39 +--------------------------------------
kernel/time/timekeeping.h | 2 --
9 files changed, 82 insertions(+), 73 deletions(-)
--
2.7.4
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 1/3] timekeeping: Remove unused timekeeping_{get,set}_tai_offset()
2017-01-28 0:59 [GIT PULL][PATCH 0/3] Timekeeping items for 4.11 John Stultz
@ 2017-01-28 0:59 ` John Stultz
2017-01-28 0:59 ` [PATCH 2/3] delay: Add explanation of udelay() inaccuracy John Stultz
2017-01-28 0:59 ` [PATCH 3/3] timers: Omit POSIX timer stuff from task_struct when disabled John Stultz
2 siblings, 0 replies; 4+ messages in thread
From: John Stultz @ 2017-01-28 0:59 UTC (permalink / raw)
To: lkml
Cc: Stephen Boyd, Thomas Gleixner, Richard Cochran, Prarit Bhargava,
Ingo Molnar, John Stultz
From: Stephen Boyd <sboyd@codeaurora.org>
The last caller to timekeeping_set_tai_offset() was in commit
0b5154fb9040 (timekeeping: Simplify tai updating from
do_adjtimex, 2013-03-22) and the last caller to
timekeeping_get_tai_offset() was in commit 76f4108892d9 (hrtimer:
Cleanup hrtimer accessors to the timekepeing state, 2014-07-16).
Remove these unused functions now that we handle TAI offsets
differently.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
kernel/time/timekeeping.c | 39 +--------------------------------------
kernel/time/timekeeping.h | 2 --
2 files changed, 1 insertion(+), 40 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index db087d7e1..95b258d 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1275,27 +1275,8 @@ int timekeeping_inject_offset(struct timespec *ts)
}
EXPORT_SYMBOL(timekeeping_inject_offset);
-
-/**
- * timekeeping_get_tai_offset - Returns current TAI offset from UTC
- *
- */
-s32 timekeeping_get_tai_offset(void)
-{
- struct timekeeper *tk = &tk_core.timekeeper;
- unsigned int seq;
- s32 ret;
-
- do {
- seq = read_seqcount_begin(&tk_core.seq);
- ret = tk->tai_offset;
- } while (read_seqcount_retry(&tk_core.seq, seq));
-
- return ret;
-}
-
/**
- * __timekeeping_set_tai_offset - Lock free worker function
+ * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
*
*/
static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
@@ -1305,24 +1286,6 @@ static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
}
/**
- * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
- *
- */
-void timekeeping_set_tai_offset(s32 tai_offset)
-{
- struct timekeeper *tk = &tk_core.timekeeper;
- unsigned long flags;
-
- raw_spin_lock_irqsave(&timekeeper_lock, flags);
- write_seqcount_begin(&tk_core.seq);
- __timekeeping_set_tai_offset(tk, tai_offset);
- timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
- write_seqcount_end(&tk_core.seq);
- raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
- clock_was_set();
-}
-
-/**
* change_clocksource - Swaps clocksources if a new one is available
*
* Accumulates current time interval and initializes new clocksource
diff --git a/kernel/time/timekeeping.h b/kernel/time/timekeeping.h
index 704f595..d091467 100644
--- a/kernel/time/timekeeping.h
+++ b/kernel/time/timekeeping.h
@@ -11,8 +11,6 @@ extern ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq,
extern int timekeeping_valid_for_hres(void);
extern u64 timekeeping_max_deferment(void);
extern int timekeeping_inject_offset(struct timespec *ts);
-extern s32 timekeeping_get_tai_offset(void);
-extern void timekeeping_set_tai_offset(s32 tai_offset);
extern int timekeeping_suspend(void);
extern void timekeeping_resume(void);
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 2/3] delay: Add explanation of udelay() inaccuracy
2017-01-28 0:59 [GIT PULL][PATCH 0/3] Timekeeping items for 4.11 John Stultz
2017-01-28 0:59 ` [PATCH 1/3] timekeeping: Remove unused timekeeping_{get,set}_tai_offset() John Stultz
@ 2017-01-28 0:59 ` John Stultz
2017-01-28 0:59 ` [PATCH 3/3] timers: Omit POSIX timer stuff from task_struct when disabled John Stultz
2 siblings, 0 replies; 4+ messages in thread
From: John Stultz @ 2017-01-28 0:59 UTC (permalink / raw)
To: lkml
Cc: Russell King, David Riley, Thomas Gleixner, Richard Cochran,
Prarit Bhargava, Ingo Molnar, John Stultz
From: Russell King <rmk+kernel@armlinux.org.uk>
There seems to be some misunderstanding that udelay() and friends will
always guarantee the specified delay. This is a false understanding.
When udelay() is based on CPU cycles, it can return early for many
reasons which are detailed by Linus' reply to me in a thread in 2011:
http://lists.openwall.net/linux-kernel/2011/01/12/372
However, a udelay test module was created in 2014 which allows udelay()
to only be 0.5% fast, which is outside of the CPU-cycles udelay()
results I measured back in 2011, which were deemed to be in the "we
don't care" region.
test_udelay() should be fixed to reflect the real allowable tolerance
on udelay(), rather than 0.5%.
Cc: David Riley <davidriley@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
include/linux/delay.h | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/include/linux/delay.h b/include/linux/delay.h
index a6ecb34..2ecb3c4 100644
--- a/include/linux/delay.h
+++ b/include/linux/delay.h
@@ -5,6 +5,17 @@
* Copyright (C) 1993 Linus Torvalds
*
* Delay routines, using a pre-computed "loops_per_jiffy" value.
+ *
+ * Please note that ndelay(), udelay() and mdelay() may return early for
+ * several reasons:
+ * 1. computed loops_per_jiffy too low (due to the time taken to
+ * execute the timer interrupt.)
+ * 2. cache behaviour affecting the time it takes to execute the
+ * loop function.
+ * 3. CPU clock rate changes.
+ *
+ * Please see this thread:
+ * http://lists.openwall.net/linux-kernel/2011/01/09/56
*/
#include <linux/kernel.h>
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 3/3] timers: Omit POSIX timer stuff from task_struct when disabled
2017-01-28 0:59 [GIT PULL][PATCH 0/3] Timekeeping items for 4.11 John Stultz
2017-01-28 0:59 ` [PATCH 1/3] timekeeping: Remove unused timekeeping_{get,set}_tai_offset() John Stultz
2017-01-28 0:59 ` [PATCH 2/3] delay: Add explanation of udelay() inaccuracy John Stultz
@ 2017-01-28 0:59 ` John Stultz
2 siblings, 0 replies; 4+ messages in thread
From: John Stultz @ 2017-01-28 0:59 UTC (permalink / raw)
To: lkml
Cc: Nicolas Pitre, Thomas Gleixner, Richard Cochran, Prarit Bhargava,
Ingo Molnar, Nicolas Pitre, John Stultz
From: Nicolas Pitre <nicolas.pitre@linaro.org>
When CONFIG_POSIX_TIMERS is disabled, it is preferable to remove related
structures from struct task_struct and struct signal_struct as they
won't contain anything useful and shouldn't be relied upon by mistake.
Code still referencing those structures is also disabled here.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
fs/proc/base.c | 4 ++--
include/linux/init_task.h | 40 +++++++++++++++++++++++++---------------
include/linux/sched.h | 13 ++++++++++---
kernel/fork.c | 10 +++++++++-
kernel/sched/rt.c | 4 ++++
kernel/sched/stats.h | 32 ++++++++++++++++++++------------
6 files changed, 70 insertions(+), 33 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8e7e61b..03deeac 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2179,7 +2179,7 @@ static const struct file_operations proc_map_files_operations = {
.llseek = generic_file_llseek,
};
-#ifdef CONFIG_CHECKPOINT_RESTORE
+#if defined(CONFIG_CHECKPOINT_RESTORE) && defined(CONFIG_POSIX_TIMERS)
struct timers_private {
struct pid *pid;
struct task_struct *task;
@@ -2936,7 +2936,7 @@ static const struct pid_entry tgid_base_stuff[] = {
REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
REG("setgroups", S_IRUGO|S_IWUSR, proc_setgroups_operations),
#endif
-#ifdef CONFIG_CHECKPOINT_RESTORE
+#if defined(CONFIG_CHECKPOINT_RESTORE) && defined(CONFIG_POSIX_TIMERS)
REG("timers", S_IRUGO, proc_timers_operations),
#endif
REG("timerslack_ns", S_IRUGO|S_IWUGO, proc_pid_set_timerslack_ns_operations),
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 325f649..3a85d61 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -42,6 +42,27 @@ extern struct fs_struct init_fs;
#define INIT_PREV_CPUTIME(x)
#endif
+#ifdef CONFIG_POSIX_TIMERS
+#define INIT_POSIX_TIMERS(s) \
+ .posix_timers = LIST_HEAD_INIT(s.posix_timers),
+#define INIT_CPU_TIMERS(s) \
+ .cpu_timers = { \
+ LIST_HEAD_INIT(s.cpu_timers[0]), \
+ LIST_HEAD_INIT(s.cpu_timers[1]), \
+ LIST_HEAD_INIT(s.cpu_timers[2]), \
+ },
+#define INIT_CPUTIMER(s) \
+ .cputimer = { \
+ .cputime_atomic = INIT_CPUTIME_ATOMIC, \
+ .running = false, \
+ .checking_timer = false, \
+ },
+#else
+#define INIT_POSIX_TIMERS(s)
+#define INIT_CPU_TIMERS(s)
+#define INIT_CPUTIMER(s)
+#endif
+
#define INIT_SIGNALS(sig) { \
.nr_threads = 1, \
.thread_head = LIST_HEAD_INIT(init_task.thread_node), \
@@ -49,14 +70,10 @@ extern struct fs_struct init_fs;
.shared_pending = { \
.list = LIST_HEAD_INIT(sig.shared_pending.list), \
.signal = {{0}}}, \
- .posix_timers = LIST_HEAD_INIT(sig.posix_timers), \
- .cpu_timers = INIT_CPU_TIMERS(sig.cpu_timers), \
+ INIT_POSIX_TIMERS(sig) \
+ INIT_CPU_TIMERS(sig) \
.rlim = INIT_RLIMITS, \
- .cputimer = { \
- .cputime_atomic = INIT_CPUTIME_ATOMIC, \
- .running = false, \
- .checking_timer = false, \
- }, \
+ INIT_CPUTIMER(sig) \
INIT_PREV_CPUTIME(sig) \
.cred_guard_mutex = \
__MUTEX_INITIALIZER(sig.cred_guard_mutex), \
@@ -247,7 +264,7 @@ extern struct task_group root_task_group;
.blocked = {{0}}, \
.alloc_lock = __SPIN_LOCK_UNLOCKED(tsk.alloc_lock), \
.journal_info = NULL, \
- .cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
+ INIT_CPU_TIMERS(tsk) \
.pi_lock = __RAW_SPIN_LOCK_UNLOCKED(tsk.pi_lock), \
.timer_slack_ns = 50000, /* 50 usec default slack */ \
.pids = { \
@@ -274,13 +291,6 @@ extern struct task_group root_task_group;
}
-#define INIT_CPU_TIMERS(cpu_timers) \
-{ \
- LIST_HEAD_INIT(cpu_timers[0]), \
- LIST_HEAD_INIT(cpu_timers[1]), \
- LIST_HEAD_INIT(cpu_timers[2]), \
-}
-
/* Attach to the init_task data structure for proper alignment */
#define __init_task_data __attribute__((__section__(".data..init_task")))
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4d19052..e8f6af5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -734,13 +734,14 @@ struct signal_struct {
unsigned int is_child_subreaper:1;
unsigned int has_child_subreaper:1;
+#ifdef CONFIG_POSIX_TIMERS
+
/* POSIX.1b Interval Timers */
int posix_timer_id;
struct list_head posix_timers;
/* ITIMER_REAL timer for the process */
struct hrtimer real_timer;
- struct pid *leader_pid;
ktime_t it_real_incr;
/*
@@ -759,12 +760,16 @@ struct signal_struct {
/* Earliest-expiration cache. */
struct task_cputime cputime_expires;
+ struct list_head cpu_timers[3];
+
+#endif
+
+ struct pid *leader_pid;
+
#ifdef CONFIG_NO_HZ_FULL
atomic_t tick_dep_mask;
#endif
- struct list_head cpu_timers[3];
-
struct pid *tty_old_pgrp;
/* boolean value for session group leader */
@@ -1681,8 +1686,10 @@ struct task_struct {
/* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
unsigned long min_flt, maj_flt;
+#ifdef CONFIG_POSIX_TIMERS
struct task_cputime cputime_expires;
struct list_head cpu_timers[3];
+#endif
/* process credentials */
const struct cred __rcu *ptracer_cred; /* Tracer's credentials at attach */
diff --git a/kernel/fork.c b/kernel/fork.c
index 11c5c8a..105c667 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1304,6 +1304,7 @@ void __cleanup_sighand(struct sighand_struct *sighand)
}
}
+#ifdef CONFIG_POSIX_TIMERS
/*
* Initialize POSIX timer handling for a thread group.
*/
@@ -1322,6 +1323,9 @@ static void posix_cpu_timers_init_group(struct signal_struct *sig)
INIT_LIST_HEAD(&sig->cpu_timers[1]);
INIT_LIST_HEAD(&sig->cpu_timers[2]);
}
+#else
+static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { }
+#endif
static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
{
@@ -1346,11 +1350,11 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
init_waitqueue_head(&sig->wait_chldexit);
sig->curr_target = tsk;
init_sigpending(&sig->shared_pending);
- INIT_LIST_HEAD(&sig->posix_timers);
seqlock_init(&sig->stats_lock);
prev_cputime_init(&sig->prev_cputime);
#ifdef CONFIG_POSIX_TIMERS
+ INIT_LIST_HEAD(&sig->posix_timers);
hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
sig->real_timer.function = it_real_fn;
#endif
@@ -1425,6 +1429,7 @@ static void rt_mutex_init_task(struct task_struct *p)
#endif
}
+#ifdef CONFIG_POSIX_TIMERS
/*
* Initialize POSIX timer handling for a single task.
*/
@@ -1437,6 +1442,9 @@ static void posix_cpu_timers_init(struct task_struct *tsk)
INIT_LIST_HEAD(&tsk->cpu_timers[1]);
INIT_LIST_HEAD(&tsk->cpu_timers[2]);
}
+#else
+static inline void posix_cpu_timers_init(struct task_struct *tsk) { }
+#endif
static inline void
init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 2516b8d..a688a82 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2246,6 +2246,7 @@ prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
}
}
+#ifdef CONFIG_POSIX_TIMERS
static void watchdog(struct rq *rq, struct task_struct *p)
{
unsigned long soft, hard;
@@ -2267,6 +2268,9 @@ static void watchdog(struct rq *rq, struct task_struct *p)
p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
}
}
+#else
+static inline void watchdog(struct rq *rq, struct task_struct *p) { }
+#endif
static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
{
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 34659a8..c69a987 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -172,18 +172,19 @@ sched_info_switch(struct rq *rq,
*/
/**
- * cputimer_running - return true if cputimer is running
+ * get_running_cputimer - return &tsk->signal->cputimer if cputimer is running
*
* @tsk: Pointer to target task.
*/
-static inline bool cputimer_running(struct task_struct *tsk)
-
+#ifdef CONFIG_POSIX_TIMERS
+static inline
+struct thread_group_cputimer *get_running_cputimer(struct task_struct *tsk)
{
struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
/* Check if cputimer isn't running. This is accessed without locking. */
if (!READ_ONCE(cputimer->running))
- return false;
+ return NULL;
/*
* After we flush the task's sum_exec_runtime to sig->sum_sched_runtime
@@ -200,10 +201,17 @@ static inline bool cputimer_running(struct task_struct *tsk)
* clock delta is behind the expiring timer value.
*/
if (unlikely(!tsk->sighand))
- return false;
+ return NULL;
- return true;
+ return cputimer;
+}
+#else
+static inline
+struct thread_group_cputimer *get_running_cputimer(struct task_struct *tsk)
+{
+ return NULL;
}
+#endif
/**
* account_group_user_time - Maintain utime for a thread group.
@@ -218,9 +226,9 @@ static inline bool cputimer_running(struct task_struct *tsk)
static inline void account_group_user_time(struct task_struct *tsk,
cputime_t cputime)
{
- struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+ struct thread_group_cputimer *cputimer = get_running_cputimer(tsk);
- if (!cputimer_running(tsk))
+ if (!cputimer)
return;
atomic64_add(cputime, &cputimer->cputime_atomic.utime);
@@ -239,9 +247,9 @@ static inline void account_group_user_time(struct task_struct *tsk,
static inline void account_group_system_time(struct task_struct *tsk,
cputime_t cputime)
{
- struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+ struct thread_group_cputimer *cputimer = get_running_cputimer(tsk);
- if (!cputimer_running(tsk))
+ if (!cputimer)
return;
atomic64_add(cputime, &cputimer->cputime_atomic.stime);
@@ -260,9 +268,9 @@ static inline void account_group_system_time(struct task_struct *tsk,
static inline void account_group_exec_runtime(struct task_struct *tsk,
unsigned long long ns)
{
- struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+ struct thread_group_cputimer *cputimer = get_running_cputimer(tsk);
- if (!cputimer_running(tsk))
+ if (!cputimer)
return;
atomic64_add(ns, &cputimer->cputime_atomic.sum_exec_runtime);
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2017-01-28 1:08 UTC | newest]
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2017-01-28 0:59 [GIT PULL][PATCH 0/3] Timekeeping items for 4.11 John Stultz
2017-01-28 0:59 ` [PATCH 1/3] timekeeping: Remove unused timekeeping_{get,set}_tai_offset() John Stultz
2017-01-28 0:59 ` [PATCH 2/3] delay: Add explanation of udelay() inaccuracy John Stultz
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