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Message-Id: <1365263228-9373-1-git-send-email-kosaki.motohiro@gmail.com>
Date: Sat, 6 Apr 2013 11:47:08 -0400
From: kosaki.motohiro@...il.com
To: linux-kernel@...r.kernel.org
Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
David Miller <davem@...emloft.net>, stable@...nel.org,
Thomas Gleixner <tglx@...utronix.de>,
Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH] posix-cpu-timers: fix counting delta_exec twice
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Currently glibc rt/cpuclock2 test(*) sporadically fail. The
pseudo test code is here.
t0 = clock_gettime()
abs = t0 + sleeptime;
clock_nanosleep(TIMER_ABSTIME, abs)
t1 = clock_gettime()
assert(t1-t0 > sleeptime)
assert(t1 > abs)
Because current signal->cputimer->cputime logic can add delta_exec
twice wrongly. The first is in initialization, thread_group_cputimer()
call thread_group_cputime() and it adds delta_exec. and later,
update_curr() adds delta_exec again.
Finally, clock_nanosleep() wakes up slightly before than passed argument and it is posix violation.
This issue was introduced by commit d670ec1317 (posix-cpu-timers:
Cure SMP wobbles).
(*) http://sourceware.org/git/?p=glibc.git;a=blob;f=rt/tst-cpuclock2.c;h=6752721717f959e89c0d692b3f1ee082d507eec2;hb=HEAD
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: David Miller <davem@...emloft.net>
Cc: stable@...nel.org
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
---
fs/binfmt_elf.c | 2 +-
fs/binfmt_elf_fdpic.c | 2 +-
include/linux/sched.h | 4 ++--
kernel/posix-cpu-timers.c | 10 +++++-----
kernel/sched/core.c | 6 ++++--
kernel/sched/cputime.c | 8 ++++----
6 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 3939829..e139e18 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1321,7 +1321,7 @@ static void fill_prstatus(struct elf_prstatus *prstatus,
* This is the record for the group leader. It shows the
* group-wide total, not its individual thread total.
*/
- thread_group_cputime(p, &cputime);
+ thread_group_cputime(p, true, &cputime);
cputime_to_timeval(cputime.utime, &prstatus->pr_utime);
cputime_to_timeval(cputime.stime, &prstatus->pr_stime);
} else {
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 9c13e02..ab5b508 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1371,7 +1371,7 @@ static void fill_prstatus(struct elf_prstatus *prstatus,
* This is the record for the group leader. It shows the
* group-wide total, not its individual thread total.
*/
- thread_group_cputime(p, &cputime);
+ thread_group_cputime(p, true, &cputime);
cputime_to_timeval(cputime.utime, &prstatus->pr_utime);
cputime_to_timeval(cputime.stime, &prstatus->pr_stime);
} else {
diff --git a/include/linux/sched.h b/include/linux/sched.h
index d35d2b6..deb49f3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2001,7 +2001,7 @@ static inline void disable_sched_clock_irqtime(void) {}
#endif
extern unsigned long long
-task_sched_runtime(struct task_struct *task);
+task_sched_runtime(struct task_struct *task, bool use_delta);
/* sched_exec is called by processes performing an exec */
#ifdef CONFIG_SMP
@@ -2624,7 +2624,7 @@ static inline int spin_needbreak(spinlock_t *lock)
/*
* Thread group CPU time accounting.
*/
-void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);
+void thread_group_cputime(struct task_struct *tsk, bool use_delta, struct task_cputime *times);
void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times);
static inline void thread_group_cputime_init(struct signal_struct *sig)
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 8fd709c..948004d 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -220,7 +220,7 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
cpu->cpu = virt_ticks(p);
break;
case CPUCLOCK_SCHED:
- cpu->sched = task_sched_runtime(p);
+ cpu->sched = task_sched_runtime(p, true);
break;
}
return 0;
@@ -251,7 +251,7 @@ void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
* to synchronize the timer to the clock every time we start
* it.
*/
- thread_group_cputime(tsk, &sum);
+ thread_group_cputime(tsk, false, &sum);
raw_spin_lock_irqsave(&cputimer->lock, flags);
cputimer->running = 1;
update_gt_cputime(&cputimer->cputime, &sum);
@@ -275,15 +275,15 @@ static int cpu_clock_sample_group(const clockid_t which_clock,
default:
return -EINVAL;
case CPUCLOCK_PROF:
- thread_group_cputime(p, &cputime);
+ thread_group_cputime(p, true, &cputime);
cpu->cpu = cputime.utime + cputime.stime;
break;
case CPUCLOCK_VIRT:
- thread_group_cputime(p, &cputime);
+ thread_group_cputime(p, true, &cputime);
cpu->cpu = cputime.utime;
break;
case CPUCLOCK_SCHED:
- thread_group_cputime(p, &cputime);
+ thread_group_cputime(p, true, &cputime);
cpu->sched = cputime.sum_exec_runtime;
break;
}
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7f12624..b2c78e1 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2662,14 +2662,16 @@ unsigned long long task_delta_exec(struct task_struct *p)
* In case the task is currently running, return the runtime plus current's
* pending runtime that have not been accounted yet.
*/
-unsigned long long task_sched_runtime(struct task_struct *p)
+unsigned long long task_sched_runtime(struct task_struct *p, bool use_delta)
{
unsigned long flags;
struct rq *rq;
u64 ns = 0;
rq = task_rq_lock(p, &flags);
- ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
+ ns = p->se.sum_exec_runtime;
+ if (use_delta)
+ ns += do_task_delta_exec(p, rq);
task_rq_unlock(rq, p, &flags);
return ns;
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index e93cca9..ee72d31 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -293,7 +293,7 @@ static __always_inline bool steal_account_process_tick(void)
* Accumulate raw cputime values of dead tasks (sig->[us]time) and live
* tasks (sum on group iteration) belonging to @tsk's group.
*/
-void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
+void thread_group_cputime(struct task_struct *tsk, bool use_delta, struct task_cputime *times)
{
struct signal_struct *sig = tsk->signal;
cputime_t utime, stime;
@@ -313,7 +313,7 @@ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
task_cputime(t, &utime, &stime);
times->utime += utime;
times->stime += stime;
- times->sum_exec_runtime += task_sched_runtime(t);
+ times->sum_exec_runtime += task_sched_runtime(t, use_delta);
} while_each_thread(tsk, t);
out:
rcu_read_unlock();
@@ -459,7 +459,7 @@ void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime
{
struct task_cputime cputime;
- thread_group_cputime(p, &cputime);
+ thread_group_cputime(p, true, &cputime);
*ut = cputime.utime;
*st = cputime.stime;
@@ -594,7 +594,7 @@ void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime
{
struct task_cputime cputime;
- thread_group_cputime(p, &cputime);
+ thread_group_cputime(p, true, &cputime);
cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
}
#endif /* !CONFIG_VIRT_CPU_ACCOUNTING */
--
1.7.1
--
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