diff options
| -rw-r--r-- | Documentation/RCU/00-INDEX | 2 | ||||
| -rw-r--r-- | Documentation/RCU/stallwarn.txt | 23 | ||||
| -rw-r--r-- | kernel/rcutree.c | 26 | ||||
| -rw-r--r-- | kernel/rcutree.h | 12 | ||||
| -rw-r--r-- | kernel/rcutree_plugin.h | 12 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 30 |
6 files changed, 17 insertions, 88 deletions
diff --git a/Documentation/RCU/00-INDEX b/Documentation/RCU/00-INDEX index 71b6f500ddb9..1d7a885761f5 100644 --- a/Documentation/RCU/00-INDEX +++ b/Documentation/RCU/00-INDEX @@ -21,7 +21,7 @@ rcu.txt RTFP.txt - List of RCU papers (bibliography) going back to 1980. stallwarn.txt - - RCU CPU stall warnings (CONFIG_RCU_CPU_STALL_DETECTOR) + - RCU CPU stall warnings (module parameter rcu_cpu_stall_suppress) torture.txt - RCU Torture Test Operation (CONFIG_RCU_TORTURE_TEST) trace.txt diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index 862c08ef1fde..4e959208f736 100644 --- a/Documentation/RCU/stallwarn.txt +++ b/Documentation/RCU/stallwarn.txt @@ -1,22 +1,25 @@ Using RCU's CPU Stall Detector -The CONFIG_RCU_CPU_STALL_DETECTOR kernel config parameter enables -RCU's CPU stall detector, which detects conditions that unduly delay -RCU grace periods. The stall detector's idea of what constitutes -"unduly delayed" is controlled by a set of C preprocessor macros: +The rcu_cpu_stall_suppress module parameter enables RCU's CPU stall +detector, which detects conditions that unduly delay RCU grace periods. +This module parameter enables CPU stall detection by default, but +may be overridden via boot-time parameter or at runtime via sysfs. +The stall detector's idea of what constitutes "unduly delayed" is +controlled by a set of kernel configuration variables and cpp macros: -RCU_SECONDS_TILL_STALL_CHECK +CONFIG_RCU_CPU_STALL_TIMEOUT - This macro defines the period of time that RCU will wait from - the beginning of a grace period until it issues an RCU CPU - stall warning. This time period is normally ten seconds. + This kernel configuration parameter defines the period of time + that RCU will wait from the beginning of a grace period until it + issues an RCU CPU stall warning. This time period is normally + ten seconds. RCU_SECONDS_TILL_STALL_RECHECK This macro defines the period of time that RCU will wait after issuing a stall warning until it issues another stall warning - for the same stall. This time period is normally set to thirty - seconds. + for the same stall. This time period is normally set to three + times the check interval plus thirty seconds. RCU_STALL_RAT_DELAY diff --git a/kernel/rcutree.c b/kernel/rcutree.c index dd4aea806f8e..18f7a593d4c7 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -140,10 +140,8 @@ module_param(blimit, int, 0); module_param(qhimark, int, 0); module_param(qlowmark, int, 0); -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR -int rcu_cpu_stall_suppress __read_mostly = RCU_CPU_STALL_SUPPRESS_INIT; +int rcu_cpu_stall_suppress __read_mostly; module_param(rcu_cpu_stall_suppress, int, 0644); -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ static void force_quiescent_state(struct rcu_state *rsp, int relaxed); static int rcu_pending(int cpu); @@ -450,8 +448,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) #endif /* #else #ifdef CONFIG_NO_HZ */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR - int rcu_cpu_stall_suppress __read_mostly; static void record_gp_stall_check_time(struct rcu_state *rsp) @@ -587,26 +583,6 @@ static void __init check_cpu_stall_init(void) atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); } -#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - -static void record_gp_stall_check_time(struct rcu_state *rsp) -{ -} - -static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) -{ -} - -void rcu_cpu_stall_reset(void) -{ -} - -static void __init check_cpu_stall_init(void) -{ -} - -#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - /* * Update CPU-local rcu_data state to record the newly noticed grace period. * This is used both when we started the grace period and when we notice diff --git a/kernel/rcutree.h b/kernel/rcutree.h index e8f057e44e3e..e1a6663c0155 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -254,7 +254,6 @@ struct rcu_data { #endif /* #else #ifdef CONFIG_NO_HZ */ #define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR #ifdef CONFIG_PROVE_RCU #define RCU_STALL_DELAY_DELTA (5 * HZ) @@ -272,13 +271,6 @@ struct rcu_data { /* scheduling clock irq */ /* before ratting on them. */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR_RUNNABLE -#define RCU_CPU_STALL_SUPPRESS_INIT 0 -#else -#define RCU_CPU_STALL_SUPPRESS_INIT 1 -#endif - -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ /* * RCU global state, including node hierarchy. This hierarchy is @@ -325,12 +317,10 @@ struct rcu_state { /* due to lock unavailable. */ unsigned long n_force_qs_ngp; /* Number of calls leaving */ /* due to no GP active. */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR unsigned long gp_start; /* Time at which GP started, */ /* but in jiffies. */ unsigned long jiffies_stall; /* Time at which to check */ /* for CPU stalls. */ -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ char *name; /* Name of structure. */ }; @@ -366,11 +356,9 @@ static int rcu_preempted_readers(struct rcu_node *rnp); static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags); #endif /* #ifdef CONFIG_HOTPLUG_CPU */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR static void rcu_print_detail_task_stall(struct rcu_state *rsp); static void rcu_print_task_stall(struct rcu_node *rnp); static void rcu_preempt_stall_reset(void); -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); #ifdef CONFIG_HOTPLUG_CPU static int rcu_preempt_offline_tasks(struct rcu_state *rsp, diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index a3638710dc67..38426ef1bcd6 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -54,10 +54,6 @@ static void __init rcu_bootup_announce_oddness(void) #ifdef CONFIG_RCU_TORTURE_TEST_RUNNABLE printk(KERN_INFO "\tRCU torture testing starts during boot.\n"); #endif -#ifndef CONFIG_RCU_CPU_STALL_DETECTOR - printk(KERN_INFO - "\tRCU-based detection of stalled CPUs is disabled.\n"); -#endif #if defined(CONFIG_TREE_PREEMPT_RCU) && !defined(CONFIG_RCU_CPU_STALL_VERBOSE) printk(KERN_INFO "\tVerbose stalled-CPUs detection is disabled.\n"); #endif @@ -356,8 +352,6 @@ void __rcu_read_unlock(void) } EXPORT_SYMBOL_GPL(__rcu_read_unlock); -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR - #ifdef CONFIG_RCU_CPU_STALL_VERBOSE /* @@ -430,8 +424,6 @@ static void rcu_preempt_stall_reset(void) rcu_preempt_state.jiffies_stall = jiffies + ULONG_MAX / 2; } -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - /* * Check that the list of blocked tasks for the newly completed grace * period is in fact empty. It is a serious bug to complete a grace @@ -862,8 +854,6 @@ static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags) #endif /* #ifdef CONFIG_HOTPLUG_CPU */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR - /* * Because preemptable RCU does not exist, we never have to check for * tasks blocked within RCU read-side critical sections. @@ -888,8 +878,6 @@ static void rcu_preempt_stall_reset(void) { } -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - /* * Because there is no preemptable RCU, there can be no readers blocked, * so there is no need to check for blocked tasks. So check only for diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c768bcdda1b7..93ce6de3300d 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -875,22 +875,9 @@ config RCU_TORTURE_TEST_RUNNABLE Say N here if you want the RCU torture tests to start only after being manually enabled via /proc. -config RCU_CPU_STALL_DETECTOR - bool "Check for stalled CPUs delaying RCU grace periods" - depends on TREE_RCU || TREE_PREEMPT_RCU - default y - help - This option causes RCU to printk information on which - CPUs are delaying the current grace period, but only when - the grace period extends for excessive time periods. - - Say N if you want to disable such checks. - - Say Y if you are unsure. - config RCU_CPU_STALL_TIMEOUT int "RCU CPU stall timeout in seconds" - depends on RCU_CPU_STALL_DETECTOR + depends on TREE_RCU || TREE_PREEMPT_RCU range 3 300 default 60 help @@ -899,22 +886,9 @@ config RCU_CPU_STALL_TIMEOUT RCU grace period persists, additional CPU stall warnings are printed at more widely spaced intervals. -config RCU_CPU_STALL_DETECTOR_RUNNABLE - bool "RCU CPU stall checking starts automatically at boot" - depends on RCU_CPU_STALL_DETECTOR - default y - help - If set, start checking for RCU CPU stalls immediately on - boot. Otherwise, RCU CPU stall checking must be manually - enabled. - - Say Y if you are unsure. - - Say N if you wish to suppress RCU CPU stall checking during boot. - config RCU_CPU_STALL_VERBOSE bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" - depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU + depends on TREE_PREEMPT_RCU default y help This option causes RCU to printk detailed per-task information |