Re: [PATCH] context_tracking: New context tracking susbsystem
On Thu, Nov 29, 2012 at 11:30:19AM +0100, Frederic Weisbecker wrote:
> 2012/11/29 Li Zhong :
> > On Tue, 2012-11-27 at 19:33 +0100, Frederic Weisbecker wrote:
> > []
> >> -
> >> - WARN_ON_ONCE(!current->mm);
> >> -
> >> - local_irq_save(flags);
> >> - rdtp = &__get_cpu_var(rcu_dynticks);
> >> - if (!rdtp->ignore_user_qs && !rdtp->in_user) {
> >> - rdtp->in_user = true;
> >> - rcu_eqs_enter(true);
> >> - }
> >
> > It seems to me that ignore_user_qs and in_user defined in struct
> > rcu_dynticks are no longer needed?
> >
> > If so, then maybe we could remove them, code below:
> >
> > ==
> > diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> > index e441b77..b8fae5d 100644
> > --- a/kernel/rcutree.c
> > +++ b/kernel/rcutree.c
> > @@ -2719,9 +2719,6 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state
> > *rsp)
> > rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
> > WARN_ON_ONCE(rdp->dynticks->dynticks_nesting !=
> > DYNTICK_TASK_EXIT_IDLE);
> > WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1);
> > -#ifdef CONFIG_RCU_USER_QS
> > - WARN_ON_ONCE(rdp->dynticks->in_user);
> > -#endif
> > rdp->cpu = cpu;
> > rdp->rsp = rsp;
> > rcu_boot_init_nocb_percpu_data(rdp);
> > diff --git a/kernel/rcutree.h b/kernel/rcutree.h
> > index 4b69291..6f21f2e 100644
> > --- a/kernel/rcutree.h
> > +++ b/kernel/rcutree.h
> > @@ -102,10 +102,6 @@ struct rcu_dynticks {
> > /* idle-period nonlazy_posted snapshot.
> > */
> > int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
> > #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
> > -#ifdef CONFIG_RCU_USER_QS
> > - bool ignore_user_qs;/* Treat userspace as extended QS or
> > not */
> > - bool in_user; /* Is the CPU in userland from RCU POV?
> > */
> > -#endif
> > };
> >
> > /* RCU's kthread states for tracing. */
> >
> >
>
> Good point. Paul, do you prefer to fold these changes into my patch or
> do we add a new one? In any case Li we need your Signed-off-by tag.
A separate patch works fine here because there should be no complaints
from compilers or tests about these. Zhong, please do send with your
Signed-off-by, and I will queue them.
Thanx, Paul
--
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/
Re: [PATCH] context_tracking: New context tracking susbsystem
2012/11/29 Li Zhong :
> On Tue, 2012-11-27 at 19:33 +0100, Frederic Weisbecker wrote:
> []
>> -
>> - WARN_ON_ONCE(!current->mm);
>> -
>> - local_irq_save(flags);
>> - rdtp = &__get_cpu_var(rcu_dynticks);
>> - if (!rdtp->ignore_user_qs && !rdtp->in_user) {
>> - rdtp->in_user = true;
>> - rcu_eqs_enter(true);
>> - }
>
> It seems to me that ignore_user_qs and in_user defined in struct
> rcu_dynticks are no longer needed?
>
> If so, then maybe we could remove them, code below:
>
> ==
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index e441b77..b8fae5d 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -2719,9 +2719,6 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state
> *rsp)
> rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
> WARN_ON_ONCE(rdp->dynticks->dynticks_nesting !=
> DYNTICK_TASK_EXIT_IDLE);
> WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1);
> -#ifdef CONFIG_RCU_USER_QS
> - WARN_ON_ONCE(rdp->dynticks->in_user);
> -#endif
> rdp->cpu = cpu;
> rdp->rsp = rsp;
> rcu_boot_init_nocb_percpu_data(rdp);
> diff --git a/kernel/rcutree.h b/kernel/rcutree.h
> index 4b69291..6f21f2e 100644
> --- a/kernel/rcutree.h
> +++ b/kernel/rcutree.h
> @@ -102,10 +102,6 @@ struct rcu_dynticks {
> /* idle-period nonlazy_posted snapshot. */
> int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
> #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
> -#ifdef CONFIG_RCU_USER_QS
> - bool ignore_user_qs;/* Treat userspace as extended QS or not
> */
> - bool in_user; /* Is the CPU in userland from RCU POV? */
> -#endif
> };
>
> /* RCU's kthread states for tracing. */
>
>
Good point. Paul, do you prefer to fold these changes into my patch or
do we add a new one? In any case Li we need your Signed-off-by tag.
Thanks.
--
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/
Re: [PATCH] context_tracking: New context tracking susbsystem
On Tue, 2012-11-27 at 19:33 +0100, Frederic Weisbecker wrote:
[]
> -
> - WARN_ON_ONCE(!current->mm);
> -
> - local_irq_save(flags);
> - rdtp = &__get_cpu_var(rcu_dynticks);
> - if (!rdtp->ignore_user_qs && !rdtp->in_user) {
> - rdtp->in_user = true;
> - rcu_eqs_enter(true);
> - }
It seems to me that ignore_user_qs and in_user defined in struct
rcu_dynticks are no longer needed?
If so, then maybe we could remove them, code below:
==
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index e441b77..b8fae5d 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -2719,9 +2719,6 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1);
-#ifdef CONFIG_RCU_USER_QS
- WARN_ON_ONCE(rdp->dynticks->in_user);
-#endif
rdp->cpu = cpu;
rdp->rsp = rsp;
rcu_boot_init_nocb_percpu_data(rdp);
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 4b69291..6f21f2e 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -102,10 +102,6 @@ struct rcu_dynticks {
/* idle-period nonlazy_posted snapshot. */
int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
-#ifdef CONFIG_RCU_USER_QS
- bool ignore_user_qs;/* Treat userspace as extended QS or not */
- bool in_user; /* Is the CPU in userland from RCU POV? */
-#endif
};
/* RCU's kthread states for tracing. */
--
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/
Re: [PATCH] context_tracking: New context tracking susbsystem
On Tue, Nov 27, 2012 at 08:50:38PM -0500, Steven Rostedt wrote: > On Tue, 2012-11-27 at 16:59 -0800, Paul E. McKenney wrote: > > On Tue, Nov 27, 2012 at 07:33:25PM +0100, Frederic Weisbecker wrote: > > > Create a new subsystem that probes on kernel boundaries > > > to keep track of the transitions between level contexts > > > with two basic initial contexts: user or kernel. > > > > > > This is an abstraction of some RCU code that use such tracking > > > to implement its userspace extended quiescent state. > > > > > > We need to pull this up from RCU into this new level of indirection > > > because this tracking is also going to be used to implement an "on > > > demand" generic virtual cputime accounting. A necessary step to > > > shutdown the tick while still accounting the cputime. > > > > I have queued this, and if it passes tests and inspection will try > > pushing it for 3.8. > > > > You can add my Reviewed-by: Steven Rostedt if you > like. Very happy to do so! ;-) Thanx, Paul -- 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/
Re: [PATCH] context_tracking: New context tracking susbsystem
On Tue, 2012-11-27 at 16:59 -0800, Paul E. McKenney wrote: > On Tue, Nov 27, 2012 at 07:33:25PM +0100, Frederic Weisbecker wrote: > > Create a new subsystem that probes on kernel boundaries > > to keep track of the transitions between level contexts > > with two basic initial contexts: user or kernel. > > > > This is an abstraction of some RCU code that use such tracking > > to implement its userspace extended quiescent state. > > > > We need to pull this up from RCU into this new level of indirection > > because this tracking is also going to be used to implement an "on > > demand" generic virtual cputime accounting. A necessary step to > > shutdown the tick while still accounting the cputime. > > I have queued this, and if it passes tests and inspection will try > pushing it for 3.8. > You can add my Reviewed-by: Steven Rostedt if you like. -- Steve -- 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/
Re: [PATCH] context_tracking: New context tracking susbsystem
On Tue, Nov 27, 2012 at 07:33:25PM +0100, Frederic Weisbecker wrote:
> Create a new subsystem that probes on kernel boundaries
> to keep track of the transitions between level contexts
> with two basic initial contexts: user or kernel.
>
> This is an abstraction of some RCU code that use such tracking
> to implement its userspace extended quiescent state.
>
> We need to pull this up from RCU into this new level of indirection
> because this tracking is also going to be used to implement an "on
> demand" generic virtual cputime accounting. A necessary step to
> shutdown the tick while still accounting the cputime.
I have queued this, and if it passes tests and inspection will try
pushing it for 3.8.
Thanx, Paul
> Signed-off-by: Frederic Weisbecker
> Cc: Andrew Morton
> Cc: H. Peter Anvin
> Cc: Ingo Molnar
> Cc: Paul E. McKenney
> Cc: Peter Zijlstra
> Cc: Steven Rostedt
> Cc: Thomas Gleixner
> Cc: Li Zhong
> Cc: Gilad Ben-Yossef gi...@benyossef.com
> ---
> Changes since last version address Gilad's comments and include ifdef fixes.
> Also CONTEXT_TRACKING_FORCE option has been moved below RCU user mode config
> as it's the only user for now.
>
> arch/Kconfig | 15 ++--
> arch/x86/Kconfig |2 +-
> arch/x86/include/asm/{rcu.h => context_tracking.h} | 15 ++--
> arch/x86/kernel/entry_64.S |2 +-
> arch/x86/kernel/ptrace.c |8 +-
> arch/x86/kernel/signal.c |5 +-
> arch/x86/kernel/traps.c|2 +-
> arch/x86/mm/fault.c|2 +-
> include/linux/context_tracking.h | 18
> include/linux/rcupdate.h |2 -
> init/Kconfig | 28
> kernel/Makefile|1 +
> kernel/context_tracking.c | 83
>
> kernel/rcutree.c | 64 +---
> kernel/sched/core.c| 11 ++-
> 15 files changed, 150 insertions(+), 108 deletions(-)
> rename arch/x86/include/asm/{rcu.h => context_tracking.h} (63%)
> create mode 100644 include/linux/context_tracking.h
> create mode 100644 kernel/context_tracking.c
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 366ec06..cc74aae 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -300,15 +300,16 @@ config SECCOMP_FILTER
>
> See Documentation/prctl/seccomp_filter.txt for details.
>
> -config HAVE_RCU_USER_QS
> +config HAVE_CONTEXT_TRACKING
> bool
> help
> - Provide kernel entry/exit hooks necessary for userspace
> - RCU extended quiescent state. Syscalls need to be wrapped inside
> - rcu_user_exit()-rcu_user_enter() through the slow path using
> - TIF_NOHZ flag. Exceptions handlers must be wrapped as well. Irqs
> - are already protected inside rcu_irq_enter/rcu_irq_exit() but
> - preemption or signal handling on irq exit still need to be protected.
> + Provide kernel/user boundaries probes necessary for subsystems
> + that need it, such as userspace RCU extended quiescent state.
> + Syscalls need to be wrapped inside user_exit()-user_enter() through
> + the slow path using TIF_NOHZ flag. Exceptions handlers must be
> + wrapped as well. Irqs are already protected inside
> + rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
> + irq exit still need to be protected.
>
> config HAVE_VIRT_CPU_ACCOUNTING
> bool
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 46c3bff..110cfad 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -106,7 +106,7 @@ config X86
> select KTIME_SCALAR if X86_32
> select GENERIC_STRNCPY_FROM_USER
> select GENERIC_STRNLEN_USER
> - select HAVE_RCU_USER_QS if X86_64
> + select HAVE_CONTEXT_TRACKING if X86_64
> select HAVE_IRQ_TIME_ACCOUNTING
> select GENERIC_KERNEL_THREAD
> select GENERIC_KERNEL_EXECVE
> diff --git a/arch/x86/include/asm/rcu.h
> b/arch/x86/include/asm/context_tracking.h
> similarity index 63%
> rename from arch/x86/include/asm/rcu.h
> rename to arch/x86/include/asm/context_tracking.h
> index d1ac07a..1616562 100644
> --- a/arch/x86/include/asm/rcu.h
> +++ b/arch/x86/include/asm/context_tracking.h
> @@ -1,27 +1,26 @@
> -#ifndef _ASM_X86_RCU_H
> -#define _ASM_X86_RCU_H
> +#ifndef _ASM_X86_CONTEXT_TRACKING_H
> +#define _ASM_X86_CONTEXT_TRACKING_H
>
> #ifndef __ASSEMBLY__
> -
> -#include
> +#include
> #include
>
> static inline void exception_enter(struct pt_regs *regs)
> {
> - rcu_user_exit();
> + user_exit();
> }
>
> static inline void exception_exit(struct pt_regs *regs)
> {
> -#ifdef CONFIG_RCU_USER_QS
>
