From: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
Currently glibc's rt/tst-cputimer1 testcase sporadically fails because
a timer created by timer_create() may fire earlier than specified.
posix_cpu_timer_set() uses "val" as current time for three purpose. 1)
initialize sig->cputimer. 2) calculation "old" val. 3) calculations an
expires.
(1) and (2) should only use committed time (i.e. without delta_exec)
because run_posix_cpu_timers() don't care of delta_exec and we need
consistency, but (3) need exact current time (aka cpu clock time) because
an expires should be "now + timeout" by definition.
This patch distinguishes between two kinds of "now".
Cc: Olivier Langlois <oliv...@trillion01.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Ingo Molnar <mi...@kernel.org>
Acked-by: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
---
include/linux/kernel_stat.h | 5 -----
kernel/posix-cpu-timers.c | 14 ++++++++++++--
kernel/sched/core.c | 13 -------------
3 files changed, 12 insertions(+), 20 deletions(-)
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index ed5f6ed..f5d4fdf 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -117,11 +117,6 @@ static inline unsigned int kstat_cpu_irqs_sum(unsigned int
cpu)
return kstat_cpu(cpu).irqs_sum;
}
-/*
- * Lock/unlock the current runqueue - to extract task statistics:
- */
-extern unsigned long long task_delta_exec(struct task_struct *);
-
extern void account_user_time(struct task_struct *, cputime_t, cputime_t);
extern void account_system_time(struct task_struct *, int, cputime_t,
cputime_t);
extern void account_steal_time(cputime_t);
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index e56be4c..98f354e 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -635,7 +635,7 @@ static int cpu_timer_sample_group(const clockid_t
which_clock,
cpu->cpu = cputime.utime;
break;
case CPUCLOCK_SCHED:
- cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
+ cpu->sched = cputime.sum_exec_runtime;
break;
}
return 0;
@@ -749,7 +749,17 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int
flags,
}
if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
- cpu_time_add(timer->it_clock, &new_expires, val);
+ union cpu_time_count now;
+
+ /*
+ * The expires is "now + timeout" by definition. So,
+ * we need exact current time.
+ */
+ if (CPUCLOCK_PERTHREAD(timer->it_clock))
+ now = val;
+ else
+ cpu_clock_sample_group(timer->it_clock, p, &now);
+ cpu_time_add(timer->it_clock, &new_expires, now);
}
/*
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ad3339f..b817e6d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2646,19 +2646,6 @@ static u64 do_task_delta_exec(struct task_struct *p,
struct rq *rq)
return ns;
}
-unsigned long long task_delta_exec(struct task_struct *p)
-{
- unsigned long flags;
- struct rq *rq;
- u64 ns = 0;
-
- rq = task_rq_lock(p, &flags);
- ns = do_task_delta_exec(p, rq);
- task_rq_unlock(rq, p, &flags);
-
- return ns;
-}
-
/*
* Return accounted runtime for the task.
* In case the task is currently running, return the runtime plus current's
--
1.7.1
--
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