From: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com> Currently glibc rt/tst-cpuclock2 test(*) sporadically fails because scheduler delta can be accounted twice from thread_group_cputimer() and account_group_exec_runtime().
Finally, clock_nanosleep() wakes up earlier than an argument. This 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: Olivier Langlois <oliv...@trillion01.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Frederic Weisbecker <fweis...@gmail.com> Cc: Ingo Molnar <mi...@kernel.org> Signed-off-by: Peter Zijlstra <pet...@infradead.org> Signed-off-by: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com> --- fs/binfmt_elf.c | 2 +- fs/binfmt_elf_fdpic.c | 2 +- include/linux/sched.h | 4 ++-- kernel/posix-cpu-timers.c | 15 ++++++++++----- kernel/sched/core.c | 6 ++++-- kernel/sched/cputime.c | 6 +++--- 6 files changed, 21 insertions(+), 14 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index f8a0b0e..9f7e13a 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1326,7 +1326,7 @@ 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 c166f32..fbcaeeb 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -1368,7 +1368,7 @@ 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 178a8d9..4878579 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1841,7 +1841,7 @@ 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 add_delta); /* sched_exec is called by processes performing an exec */ #ifdef CONFIG_SMP @@ -2502,7 +2502,7 @@ static inline void current_clr_polling(void) { } /* * 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 add_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 42670e9..25447c5 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -237,7 +237,7 @@ 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; @@ -267,8 +267,13 @@ void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times) * values through the TIMER_ABSTIME flag, therefore we have * to synchronize the timer to the clock every time we start * it. + * + * Do not add the current delta, because + * account_group_exec_runtime() will also this delta and we + * wouldn't want to double account time and get ahead of + * ourselves. */ - 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); @@ -292,15 +297,15 @@ 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 58453b8..a1e823b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2699,14 +2699,16 @@ 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 add_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 (add_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 cc2dc3e..3ca432c 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -277,7 +277,7 @@ 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 add_delta, struct task_cputime *times) { struct signal_struct *sig = tsk->signal; cputime_t utime, stime; @@ -297,7 +297,7 @@ 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, add_delta); } while_each_thread(tsk, t); out: rcu_read_unlock(); @@ -628,7 +628,7 @@ 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_NATIVE */ -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
