[PATCH tip/core/rcu 04/12] rcu: Export RCU_FAST_NO_HZ parameters to sysfs
From: "Paul E. McKenney"
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
Signed-off-by: Paul E. McKenney
---
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 c016444..28185ad 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 = >idle_gp_timer;
--
1.7.8
--
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[PATCH tip/core/rcu 04/12] rcu: Export RCU_FAST_NO_HZ parameters to sysfs
From: Paul E. McKenney paul.mcken...@linaro.org
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.randh...@arm.com
Signed-off-by: Paul E. McKenney paul...@linux.vnet.ibm.com
---
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 c016444..28185ad 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;
--
1.7.8
--
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