On 12-12-29 11:42 AM, Frederic Weisbecker wrote:
> Allow to dynamically switch between tick and virtual based cputime accounting.
> This way we can provide a kind of "on-demand" virtual based cputime
> accounting. In this mode, the kernel will rely on the user hooks
> subsystem to dynamically hook on kernel boundaries.
>
> This is in preparation for beeing able to stop the timer tick further
> idle. Doing so will depend on CONFIG_VIRT_CPU_ACCOUNTING which makes
s/beeing/being/ -- also I know what you mean, but it may not be
100% clear to everyone -- perhaps "...for being able to stop the
timer tick in more places than just the idle state."
> it possible to account the cputime without the tick by hooking on
> kernel/user boundaries.
>
> Depending whether the tick is stopped or not, we can switch between
> tick and vtime based accounting anytime in order to minimize the
> overhead associated to user hooks.
>
> Signed-off-by: Frederic Weisbecker <fweis...@gmail.com>
> Cc: Alessio Igor Bogani <abog...@kernel.org>
> Cc: Andrew Morton <a...@linux-foundation.org>
> Cc: Chris Metcalf <cmetc...@tilera.com>
> Cc: Christoph Lameter <c...@linux.com>
> Cc: Geoff Levand <ge...@infradead.org>
> Cc: Gilad Ben Yossef <gi...@benyossef.com>
> Cc: Hakan Akkan <hakanak...@gmail.com>
> Cc: Ingo Molnar <mi...@kernel.org>
> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> Cc: Paul Gortmaker <paul.gortma...@windriver.com>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Steven Rostedt <rost...@goodmis.org>
> Cc: Thomas Gleixner <t...@linutronix.de>
> ---
> include/linux/kernel_stat.h | 2 +-
> include/linux/sched.h | 4 +-
> include/linux/vtime.h | 8 ++++++
> init/Kconfig | 6 ++++
> kernel/fork.c | 2 +-
> kernel/sched/cputime.c | 58 +++++++++++++++++++++++++++---------------
> kernel/time/tick-sched.c | 5 +++-
> 7 files changed, 59 insertions(+), 26 deletions(-)
>
> diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
> index 66b7078..ed5f6ed 100644
> --- a/include/linux/kernel_stat.h
> +++ b/include/linux/kernel_stat.h
> @@ -127,7 +127,7 @@ extern void account_system_time(struct task_struct *,
> int, cputime_t, cputime_t)
> extern void account_steal_time(cputime_t);
> extern void account_idle_time(cputime_t);
>
> -#ifdef CONFIG_VIRT_CPU_ACCOUNTING
> +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
> static inline void account_process_tick(struct task_struct *tsk, int user)
> {
> vtime_account_user(tsk);
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 206bb08..66b2344 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -605,7 +605,7 @@ struct signal_struct {
> cputime_t utime, stime, cutime, cstime;
> cputime_t gtime;
> cputime_t cgtime;
> -#ifndef CONFIG_VIRT_CPU_ACCOUNTING
> +#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
> struct cputime prev_cputime;
> #endif
> unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
> @@ -1365,7 +1365,7 @@ struct task_struct {
>
> cputime_t utime, stime, utimescaled, stimescaled;
> cputime_t gtime;
> -#ifndef CONFIG_VIRT_CPU_ACCOUNTING
> +#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
> struct cputime prev_cputime;
> #endif
> unsigned long nvcsw, nivcsw; /* context switch counts */
> diff --git a/include/linux/vtime.h b/include/linux/vtime.h
> index 1151960..e57020d 100644
> --- a/include/linux/vtime.h
> +++ b/include/linux/vtime.h
> @@ -10,12 +10,20 @@ extern void vtime_account_system_irqsafe(struct
> task_struct *tsk);
> extern void vtime_account_idle(struct task_struct *tsk);
> extern void vtime_account_user(struct task_struct *tsk);
> extern void vtime_account(struct task_struct *tsk);
> +
> +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
> +extern bool vtime_accounting(void);
> #else
> +static inline bool vtime_accounting(void) { return true; }
> +#endif
> +
> +#else /* !CONFIG_VIRT_CPU_ACCOUNTING */
> static inline void vtime_task_switch(struct task_struct *prev) { }
> static inline void vtime_account_system(struct task_struct *tsk) { }
> static inline void vtime_account_system_irqsafe(struct task_struct *tsk) { }
> static inline void vtime_account_user(struct task_struct *tsk) { }
> static inline void vtime_account(struct task_struct *tsk) { }
> +static inline bool vtime_accounting(void) { return false; }
It wasn't 100% obvious what vtime_accounting() was doing until I
saw its definition below. I wonder if it should be something like
vtime_accounting_on() or vtime_accounting_enabled() instead?
> #endif
>
> #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
> diff --git a/init/Kconfig b/init/Kconfig
> index dad2b88..307bc35 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -342,6 +342,7 @@ config VIRT_CPU_ACCOUNTING
> bool "Deterministic task and CPU time accounting"
> depends on HAVE_VIRT_CPU_ACCOUNTING || HAVE_CONTEXT_TRACKING
> select VIRT_CPU_ACCOUNTING_GEN if !HAVE_VIRT_CPU_ACCOUNTING
> + select VIRT_CPU_ACCOUNTING_NATIVE if HAVE_VIRT_CPU_ACCOUNTING
> help
> Select this option to enable more accurate task and CPU time
> accounting. This is done by reading a CPU counter on each
> @@ -366,11 +367,16 @@ endchoice
>
> config VIRT_CPU_ACCOUNTING_GEN
> select CONTEXT_TRACKING
> + depends on VIRT_CPU_ACCOUNTING && HAVE_CONTEXT_TRACKING
Should the 2nd half of this depends been already here, i.e. introduced
with the prev. patch that created VIRT_CPU_ACCOUNTING_GEN?
Paul.
--
> bool
> help
> Implement a generic virtual based cputime accounting by using
> the context tracking subsystem.
>
> +config VIRT_CPU_ACCOUNTING_NATIVE
> + depends on VIRT_CPU_ACCOUNTING && HAVE_VIRT_CPU_ACCOUNTING
> + bool
> +
> config BSD_PROCESS_ACCT
> bool "BSD Process Accounting"
> help
> diff --git a/kernel/fork.c b/kernel/fork.c
> index a31b823..8e934d2 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1222,7 +1222,7 @@ static struct task_struct *copy_process(unsigned long
> clone_flags,
>
> p->utime = p->stime = p->gtime = 0;
> p->utimescaled = p->stimescaled = 0;
> -#ifndef CONFIG_VIRT_CPU_ACCOUNTING
> +#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
> p->prev_cputime.utime = p->prev_cputime.stime = 0;
> #endif
> #if defined(SPLIT_RSS_COUNTING)
> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> index 3749a0e..e1fcab4 100644
> --- a/kernel/sched/cputime.c
> +++ b/kernel/sched/cputime.c
> @@ -317,8 +317,6 @@ out:
> rcu_read_unlock();
> }
>
> -#ifndef CONFIG_VIRT_CPU_ACCOUNTING
> -
> #ifdef CONFIG_IRQ_TIME_ACCOUNTING
> /*
> * Account a tick to a process and cpustat
> @@ -388,6 +386,7 @@ static void irqtime_account_process_tick(struct
> task_struct *p, int user_tick,
> struct rq *rq) {}
> #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
>
> +#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
> /*
> * Account a single tick of cpu time.
> * @p: the process that the cpu time gets accounted to
> @@ -398,6 +397,11 @@ void account_process_tick(struct task_struct *p, int
> user_tick)
> cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
> struct rq *rq = this_rq();
>
> + if (vtime_accounting()) {
> + vtime_account_user(p);
> + return;
> + }
> +
> if (sched_clock_irqtime) {
> irqtime_account_process_tick(p, user_tick, rq);
> return;
> @@ -439,29 +443,13 @@ void account_idle_ticks(unsigned long ticks)
>
> account_idle_time(jiffies_to_cputime(ticks));
> }
> -
> #endif
>
> +
> /*
> * Use precise platform statistics if available:
> */
> #ifdef CONFIG_VIRT_CPU_ACCOUNTING
> -void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t
> *st)
> -{
> - *ut = p->utime;
> - *st = p->stime;
> -}
> -
> -void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
> cputime_t *st)
> -{
> - struct task_cputime cputime;
> -
> - thread_group_cputime(p, &cputime);
> -
> - *ut = cputime.utime;
> - *st = cputime.stime;
> -}
> -
> void vtime_account_system_irqsafe(struct task_struct *tsk)
> {
> unsigned long flags;
> @@ -517,8 +505,25 @@ void vtime_account(struct task_struct *tsk)
> }
> EXPORT_SYMBOL_GPL(vtime_account);
> #endif /* __ARCH_HAS_VTIME_ACCOUNT */
> +#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
>
> -#else
> +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
> +void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t
> *st)
> +{
> + *ut = p->utime;
> + *st = p->stime;
> +}
> +
> +void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
> cputime_t *st)
> +{
> + struct task_cputime cputime;
> +
> + thread_group_cputime(p, &cputime);
> +
> + *ut = cputime.utime;
> + *st = cputime.stime;
> +}
> +#else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
>
> #ifndef nsecs_to_cputime
> # define nsecs_to_cputime(__nsecs) nsecs_to_jiffies(__nsecs)
> @@ -548,6 +553,12 @@ static void cputime_adjust(struct task_cputime *curr,
> {
> cputime_t rtime, utime, total;
>
> + if (vtime_accounting()) {
> + *ut = curr->utime;
> + *st = curr->stime;
> + return;
> + }
> +
> utime = curr->utime;
> total = utime + curr->stime;
>
> @@ -601,7 +612,7 @@ void thread_group_cputime_adjusted(struct task_struct *p,
> cputime_t *ut, cputime
> thread_group_cputime(p, &cputime);
> cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
> }
> -#endif
> +#endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
>
> #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
> static DEFINE_PER_CPU(long, last_jiffies) = INITIAL_JIFFIES;
> @@ -643,6 +654,11 @@ void vtime_account_idle(struct task_struct *tsk)
> account_idle_time(delta_cpu);
> }
>
> +bool vtime_accounting(void)
> +{
> + return context_tracking_active();
> +}
> +
> static int __cpuinit vtime_cpu_notify(struct notifier_block *self,
> unsigned long action, void *hcpu)
> {
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index fb8e5e4..ad0e6fa 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -632,8 +632,11 @@ static void tick_nohz_restart_sched_tick(struct
> tick_sched *ts, ktime_t now)
>
> static void tick_nohz_account_idle_ticks(struct tick_sched *ts)
> {
> -#ifndef CONFIG_VIRT_CPU_ACCOUNTING
> +#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
> unsigned long ticks;
> +
> + if (vtime_accounting())
> + return;
> /*
> * We stopped the tick in idle. Update process times would miss the
> * time we slept as update_process_times does only a 1 tick
>
--
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/
