From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Clark Williams <clark.williams@gmail.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [RFC][PATCH RT 6/6] vtime: Convert vtime_seqlock into raw_spinlock_t and seqcount combo
Date: Wed, 26 Jun 2013 15:28:12 -0400 [thread overview]
Message-ID: <20130626193050.529670718@goodmis.org> (raw)
In-Reply-To: 20130626192806.107564905@goodmis.org
[-- Attachment #1: vtime-lock.patch --]
[-- Type: text/plain, Size: 6793 bytes --]
The vtime seqlock needs to be taken in true interrupt context on -rt.
The normal seqlocks are converted to mutexes when PREEMPT_RT_FULL is
enabled, which will break the vtime code as the calls are done from
interrupt context.
Convert the vtime seqlock into the raw_spinlock_t and seqcount combo
that can be done in interrupt context.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Index: linux-rt.git/include/linux/sched.h
===================================================================
--- linux-rt.git.orig/include/linux/sched.h
+++ linux-rt.git/include/linux/sched.h
@@ -1176,7 +1176,8 @@ struct task_struct {
struct cputime prev_cputime;
#endif
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
- seqlock_t vtime_seqlock;
+ raw_spinlock_t vtime_lock;
+ seqcount_t vtime_seq;
unsigned long long vtime_snap;
enum {
VTIME_SLEEPING = 0,
Index: linux-rt.git/kernel/sched/cputime.c
===================================================================
--- linux-rt.git.orig/kernel/sched/cputime.c
+++ linux-rt.git/kernel/sched/cputime.c
@@ -668,9 +668,11 @@ void vtime_account_system(struct task_st
if (!vtime_accounting_enabled())
return;
- write_seqlock(&tsk->vtime_seqlock);
+ raw_spin_lock(&tsk->vtime_lock);
+ write_seqcount_begin(&tsk->vtime_seq);
__vtime_account_system(tsk);
- write_sequnlock(&tsk->vtime_seqlock);
+ write_seqcount_end(&tsk->vtime_seq);
+ raw_spin_unlock(&tsk->vtime_lock);
}
void vtime_account_irq_exit(struct task_struct *tsk)
@@ -678,11 +680,13 @@ void vtime_account_irq_exit(struct task_
if (!vtime_accounting_enabled())
return;
- write_seqlock(&tsk->vtime_seqlock);
+ raw_spin_lock(&tsk->vtime_lock);
+ write_seqcount_begin(&tsk->vtime_seq);
if (context_tracking_in_user())
tsk->vtime_snap_whence = VTIME_USER;
__vtime_account_system(tsk);
- write_sequnlock(&tsk->vtime_seqlock);
+ write_seqcount_end(&tsk->vtime_seq);
+ raw_spin_unlock(&tsk->vtime_lock);
}
void vtime_account_user(struct task_struct *tsk)
@@ -694,10 +698,12 @@ void vtime_account_user(struct task_stru
delta_cpu = get_vtime_delta(tsk);
- write_seqlock(&tsk->vtime_seqlock);
+ raw_spin_lock(&tsk->vtime_lock);
+ write_seqcount_begin(&tsk->vtime_seq);
tsk->vtime_snap_whence = VTIME_SYS;
account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
- write_sequnlock(&tsk->vtime_seqlock);
+ write_seqcount_end(&tsk->vtime_seq);
+ raw_spin_unlock(&tsk->vtime_lock);
}
void vtime_user_enter(struct task_struct *tsk)
@@ -705,26 +711,32 @@ void vtime_user_enter(struct task_struct
if (!vtime_accounting_enabled())
return;
- write_seqlock(&tsk->vtime_seqlock);
+ raw_spin_lock(&tsk->vtime_lock);
+ write_seqcount_begin(&tsk->vtime_seq);
tsk->vtime_snap_whence = VTIME_USER;
__vtime_account_system(tsk);
- write_sequnlock(&tsk->vtime_seqlock);
+ write_seqcount_end(&tsk->vtime_seq);
+ raw_spin_unlock(&tsk->vtime_lock);
}
void vtime_guest_enter(struct task_struct *tsk)
{
- write_seqlock(&tsk->vtime_seqlock);
+ raw_spin_lock(&tsk->vtime_lock);
+ write_seqcount_begin(&tsk->vtime_seq);
__vtime_account_system(tsk);
current->flags |= PF_VCPU;
- write_sequnlock(&tsk->vtime_seqlock);
+ write_seqcount_end(&tsk->vtime_seq);
+ raw_spin_unlock(&tsk->vtime_lock);
}
void vtime_guest_exit(struct task_struct *tsk)
{
- write_seqlock(&tsk->vtime_seqlock);
+ raw_spin_lock(&tsk->vtime_lock);
+ write_seqcount_begin(&tsk->vtime_seq);
__vtime_account_system(tsk);
current->flags &= ~PF_VCPU;
- write_sequnlock(&tsk->vtime_seqlock);
+ write_seqcount_end(&tsk->vtime_seq);
+ raw_spin_unlock(&tsk->vtime_lock);
}
void vtime_account_idle(struct task_struct *tsk)
@@ -741,24 +753,30 @@ bool vtime_accounting_enabled(void)
void arch_vtime_task_switch(struct task_struct *prev)
{
- write_seqlock(&prev->vtime_seqlock);
+ raw_spin_lock(&prev->vtime_lock);
+ write_seqcount_begin(&prev->vtime_seq);
prev->vtime_snap_whence = VTIME_SLEEPING;
- write_sequnlock(&prev->vtime_seqlock);
+ write_seqcount_end(&prev->vtime_seq);
+ raw_spin_unlock(&prev->vtime_lock);
- write_seqlock(¤t->vtime_seqlock);
+ raw_spin_lock(¤t->vtime_lock);
+ write_seqcount_begin(¤t->vtime_seq);
current->vtime_snap_whence = VTIME_SYS;
current->vtime_snap = sched_clock_cpu(smp_processor_id());
- write_sequnlock(¤t->vtime_seqlock);
+ write_seqcount_end(¤t->vtime_seq);
+ raw_spin_unlock(¤t->vtime_lock);
}
void vtime_init_idle(struct task_struct *t, int cpu)
{
unsigned long flags;
- write_seqlock_irqsave(&t->vtime_seqlock, flags);
+ raw_spin_lock_irqsave(&t->vtime_lock, flags);
+ write_seqcount_begin(&t->vtime_seq);
t->vtime_snap_whence = VTIME_SYS;
t->vtime_snap = sched_clock_cpu(cpu);
- write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
+ write_seqcount_end(&t->vtime_seq);
+ raw_spin_unlock_irqrestore(&t->vtime_lock, flags);
}
cputime_t task_gtime(struct task_struct *t)
@@ -767,13 +785,13 @@ cputime_t task_gtime(struct task_struct
cputime_t gtime;
do {
- seq = read_seqbegin(&t->vtime_seqlock);
+ seq = read_seqcount_begin(&t->vtime_seq);
gtime = t->gtime;
if (t->flags & PF_VCPU)
gtime += vtime_delta(t);
- } while (read_seqretry(&t->vtime_seqlock, seq));
+ } while (read_seqcount_retry(&t->vtime_seq, seq));
return gtime;
}
@@ -796,7 +814,7 @@ fetch_task_cputime(struct task_struct *t
*udelta = 0;
*sdelta = 0;
- seq = read_seqbegin(&t->vtime_seqlock);
+ seq = read_seqcount_begin(&t->vtime_seq);
if (u_dst)
*u_dst = *u_src;
@@ -820,7 +838,7 @@ fetch_task_cputime(struct task_struct *t
if (t->vtime_snap_whence == VTIME_SYS)
*sdelta = delta;
}
- } while (read_seqretry(&t->vtime_seqlock, seq));
+ } while (read_seqcount_retry(&t->vtime_seq, seq));
}
Index: linux-rt.git/include/linux/init_task.h
===================================================================
--- linux-rt.git.orig/include/linux/init_task.h
+++ linux-rt.git/include/linux/init_task.h
@@ -151,7 +151,8 @@ extern struct task_group root_task_group
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
# define INIT_VTIME(tsk) \
- .vtime_seqlock = __SEQLOCK_UNLOCKED(tsk.vtime_seqlock), \
+ .vtime_lock = __RAW_SPIN_LOCK_UNLOCKED(tsk.vtime_lock), \
+ .vtime_seq = SEQCNT_ZERO, \
.vtime_snap = 0, \
.vtime_snap_whence = VTIME_SYS,
#else
Index: linux-rt.git/kernel/fork.c
===================================================================
--- linux-rt.git.orig/kernel/fork.c
+++ linux-rt.git/kernel/fork.c
@@ -1268,7 +1268,8 @@ static struct task_struct *copy_process(
p->prev_cputime.utime = p->prev_cputime.stime = 0;
#endif
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
- seqlock_init(&p->vtime_seqlock);
+ raw_spin_lock_init(&p->vtime_lock);
+ seqcount_init(&p->vtime_seq);
p->vtime_snap = 0;
p->vtime_snap_whence = VTIME_SLEEPING;
#endif
next prev parent reply other threads:[~2013-06-26 19:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-26 19:28 [RFC][PATCH RT 0/6] rt: Updates to handle some 3.10 changes Steven Rostedt
2013-06-26 19:28 ` [RFC][PATCH RT 1/6] rt,rcu: Have rcu_read_lock_sched() use locks for PREEMPT_RT Steven Rostedt
2013-06-26 20:53 ` Paul E. McKenney
2013-06-26 21:32 ` Steven Rostedt
2013-06-27 3:52 ` Mike Galbraith
2013-06-27 11:28 ` Steven Rostedt
2013-06-26 19:28 ` [RFC][PATCH RT 2/6] workqueue: Use rcu_read_lock_sched() to denote RCU synchronize_sched() location Steven Rostedt
2013-06-26 19:28 ` [RFC][PATCH RT 3/6] idr: Use migrate_disable() to stay on the current CPU Steven Rostedt
2013-06-26 19:28 ` [RFC][PATCH RT 4/6] rt,workqueue: Add local_lock_irq() call to put_pwq_unlocked() Steven Rostedt
2013-06-26 19:28 ` [RFC][PATCH RT 5/6] rt,ntp: Move call to schedule_delayed_work() to helper thread Steven Rostedt
2013-06-26 19:28 ` Steven Rostedt [this message]
2013-07-10 17:12 ` [RFC][PATCH RT 6/6] vtime: Convert vtime_seqlock into raw_spinlock_t and seqcount combo Paul Gortmaker
2013-07-11 14:30 ` Steven Rostedt
2013-06-26 19:43 ` [RFC][PATCH RT 0.5/6] locallock: Add include of percpu.h Steven Rostedt
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