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| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2012-12-12 21:35:29 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-03-26 16:04:49 +0100 |
| commit | 5e44ce35a6ec1a16522fa2099dda27aefd8a584e (patch) | |
| tree | b7e48d500cfc7ea6532f4d682a1799d346a03aac /kernel | |
| parent | rcu: Distinguish "rcuo" kthreads by RCU flavor (diff) | |
| download | linux-5e44ce35a6ec1a16522fa2099dda27aefd8a584e.tar.xz linux-5e44ce35a6ec1a16522fa2099dda27aefd8a584e.zip | |
rcu: Export RCU_FAST_NO_HZ parameters to sysfs
RCU_FAST_NO_HZ operation is controlled by four compile-time C-preprocessor
macros, but some use cases benefit greatly from runtime adjustment,
particularly when tuning devices. This commit therefore creates the
corresponding sysfs entries.
Reported-by: Robin Randhawa <robin.randhawa@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcutree_plugin.h | 31 |
1 files changed, 20 insertions, 11 deletions
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index c0164441ab92..28185ad18df3 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1617,6 +1617,15 @@ static void rcu_idle_count_callbacks_posted(void) #define RCU_IDLE_GP_DELAY 4 /* Roughly one grace period. */ #define RCU_IDLE_LAZY_GP_DELAY (6 * HZ) /* Roughly six seconds. */ +static int rcu_idle_flushes = RCU_IDLE_FLUSHES; +module_param(rcu_idle_flushes, int, 0644); +static int rcu_idle_opt_flushes = RCU_IDLE_OPT_FLUSHES; +module_param(rcu_idle_opt_flushes, int, 0644); +static int rcu_idle_gp_delay = RCU_IDLE_GP_DELAY; +module_param(rcu_idle_gp_delay, int, 0644); +static int rcu_idle_lazy_gp_delay = RCU_IDLE_LAZY_GP_DELAY; +module_param(rcu_idle_lazy_gp_delay, int, 0644); + extern int tick_nohz_enabled; /* @@ -1696,10 +1705,10 @@ int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies) } /* Set up for the possibility that RCU will post a timer. */ if (rcu_cpu_has_nonlazy_callbacks(cpu)) { - *delta_jiffies = round_up(RCU_IDLE_GP_DELAY + jiffies, - RCU_IDLE_GP_DELAY) - jiffies; + *delta_jiffies = round_up(rcu_idle_gp_delay + jiffies, + rcu_idle_gp_delay) - jiffies; } else { - *delta_jiffies = jiffies + RCU_IDLE_LAZY_GP_DELAY; + *delta_jiffies = jiffies + rcu_idle_lazy_gp_delay; *delta_jiffies = round_jiffies(*delta_jiffies) - jiffies; } return 0; @@ -1805,11 +1814,11 @@ static void rcu_prepare_for_idle(int cpu) if (rcu_cpu_has_nonlazy_callbacks(cpu)) { trace_rcu_prep_idle("User dyntick with callbacks"); rdtp->idle_gp_timer_expires = - round_up(jiffies + RCU_IDLE_GP_DELAY, - RCU_IDLE_GP_DELAY); + round_up(jiffies + rcu_idle_gp_delay, + rcu_idle_gp_delay); } else if (rcu_cpu_has_callbacks(cpu)) { rdtp->idle_gp_timer_expires = - round_jiffies(jiffies + RCU_IDLE_LAZY_GP_DELAY); + round_jiffies(jiffies + rcu_idle_lazy_gp_delay); trace_rcu_prep_idle("User dyntick with lazy callbacks"); } else { return; @@ -1861,8 +1870,8 @@ static void rcu_prepare_for_idle(int cpu) /* Check and update the ->dyntick_drain sequencing. */ if (rdtp->dyntick_drain <= 0) { /* First time through, initialize the counter. */ - rdtp->dyntick_drain = RCU_IDLE_FLUSHES; - } else if (rdtp->dyntick_drain <= RCU_IDLE_OPT_FLUSHES && + rdtp->dyntick_drain = rcu_idle_flushes; + } else if (rdtp->dyntick_drain <= rcu_idle_opt_flushes && !rcu_pending(cpu) && !local_softirq_pending()) { /* Can we go dyntick-idle despite still having callbacks? */ @@ -1871,11 +1880,11 @@ static void rcu_prepare_for_idle(int cpu) if (rcu_cpu_has_nonlazy_callbacks(cpu)) { trace_rcu_prep_idle("Dyntick with callbacks"); rdtp->idle_gp_timer_expires = - round_up(jiffies + RCU_IDLE_GP_DELAY, - RCU_IDLE_GP_DELAY); + round_up(jiffies + rcu_idle_gp_delay, + rcu_idle_gp_delay); } else { rdtp->idle_gp_timer_expires = - round_jiffies(jiffies + RCU_IDLE_LAZY_GP_DELAY); + round_jiffies(jiffies + rcu_idle_lazy_gp_delay); trace_rcu_prep_idle("Dyntick with lazy callbacks"); } tp = &rdtp->idle_gp_timer; |