From 52494535103986dbbf689b44d8c2c7efe2132b16 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 14 Nov 2012 16:26:40 -0800 Subject: rcu: Reduce rcutorture tracing Currently, rcutorture traces every read-side access. This can be problematic because even a two-minute rcutorture run on a two-CPU system can generate 28,853,363 reads. Normally, only a failing read is of interest, so this commit traces adjusts rcutorture's tracing to only trace failing reads. The resulting event tracing records the time and the ->completed value captured at the beginning of the RCU read-side critical section, allowing correlation with other event-tracing messages. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett [ paulmck: Add fix to build problem located by Randy Dunlap based on diagnosis by Steven Rostedt. ] --- lib/Kconfig.debug | 1 + 1 file changed, 1 insertion(+) (limited to 'lib') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 3a35309..7d83f52 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1008,6 +1008,7 @@ config RCU_CPU_STALL_INFO config RCU_TRACE bool "Enable tracing for RCU" depends on DEBUG_KERNEL + select TRACE_CLOCK help This option provides tracing in RCU which presents stats in debugfs for debugging RCU implementation. -- cgit v1.1 From 2f03e3ca74a7f8b17ce626d337d321163dce2dad Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Mon, 7 Jan 2013 08:19:23 -0800 Subject: rcu: Consolidate debugging Kconfig options The RCU-related debugging Kconfig options are in two different places, and consume too much screen real estate. This commit therefore consolidates them into their own menu. Signed-off-by: Dave Hansen Signed-off-by: Paul E. McKenney --- lib/Kconfig.debug | 114 ++++++++++++++++++++++++++++-------------------------- 1 file changed, 59 insertions(+), 55 deletions(-) (limited to 'lib') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 3a35309..122db3d 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -605,61 +605,6 @@ config PROVE_LOCKING For more details, see Documentation/lockdep-design.txt. -config PROVE_RCU - bool "RCU debugging: prove RCU correctness" - depends on PROVE_LOCKING - default n - help - This feature enables lockdep extensions that check for correct - use of RCU APIs. This is currently under development. Say Y - if you want to debug RCU usage or help work on the PROVE_RCU - feature. - - Say N if you are unsure. - -config PROVE_RCU_REPEATEDLY - bool "RCU debugging: don't disable PROVE_RCU on first splat" - depends on PROVE_RCU - default n - help - By itself, PROVE_RCU will disable checking upon issuing the - first warning (or "splat"). This feature prevents such - disabling, allowing multiple RCU-lockdep warnings to be printed - on a single reboot. - - Say Y to allow multiple RCU-lockdep warnings per boot. - - Say N if you are unsure. - -config PROVE_RCU_DELAY - bool "RCU debugging: preemptible RCU race provocation" - depends on DEBUG_KERNEL && PREEMPT_RCU - default n - help - There is a class of races that involve an unlikely preemption - of __rcu_read_unlock() just after ->rcu_read_lock_nesting has - been set to INT_MIN. This feature inserts a delay at that - point to increase the probability of these races. - - Say Y to increase probability of preemption of __rcu_read_unlock(). - - Say N if you are unsure. - -config SPARSE_RCU_POINTER - bool "RCU debugging: sparse-based checks for pointer usage" - default n - help - This feature enables the __rcu sparse annotation for - RCU-protected pointers. This annotation will cause sparse - to flag any non-RCU used of annotated pointers. This can be - helpful when debugging RCU usage. Please note that this feature - is not intended to enforce code cleanliness; it is instead merely - a debugging aid. - - Say Y to make sparse flag questionable use of RCU-protected pointers - - Say N if you are unsure. - config LOCKDEP bool depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT @@ -937,6 +882,63 @@ config BOOT_PRINTK_DELAY BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect what it believes to be lockup conditions. +menu "RCU Debugging" + +config PROVE_RCU + bool "RCU debugging: prove RCU correctness" + depends on PROVE_LOCKING + default n + help + This feature enables lockdep extensions that check for correct + use of RCU APIs. This is currently under development. Say Y + if you want to debug RCU usage or help work on the PROVE_RCU + feature. + + Say N if you are unsure. + +config PROVE_RCU_REPEATEDLY + bool "RCU debugging: don't disable PROVE_RCU on first splat" + depends on PROVE_RCU + default n + help + By itself, PROVE_RCU will disable checking upon issuing the + first warning (or "splat"). This feature prevents such + disabling, allowing multiple RCU-lockdep warnings to be printed + on a single reboot. + + Say Y to allow multiple RCU-lockdep warnings per boot. + + Say N if you are unsure. + +config PROVE_RCU_DELAY + bool "RCU debugging: preemptible RCU race provocation" + depends on DEBUG_KERNEL && PREEMPT_RCU + default n + help + There is a class of races that involve an unlikely preemption + of __rcu_read_unlock() just after ->rcu_read_lock_nesting has + been set to INT_MIN. This feature inserts a delay at that + point to increase the probability of these races. + + Say Y to increase probability of preemption of __rcu_read_unlock(). + + Say N if you are unsure. + +config SPARSE_RCU_POINTER + bool "RCU debugging: sparse-based checks for pointer usage" + default n + help + This feature enables the __rcu sparse annotation for + RCU-protected pointers. This annotation will cause sparse + to flag any non-RCU used of annotated pointers. This can be + helpful when debugging RCU usage. Please note that this feature + is not intended to enforce code cleanliness; it is instead merely + a debugging aid. + + Say Y to make sparse flag questionable use of RCU-protected pointers + + Say N if you are unsure. + config RCU_TORTURE_TEST tristate "torture tests for RCU" depends on DEBUG_KERNEL @@ -1015,6 +1017,8 @@ config RCU_TRACE Say Y here if you want to enable RCU tracing Say N if you are unsure. +endmenu # "RCU Debugging" + config KPROBES_SANITY_TEST bool "Kprobes sanity tests" depends on DEBUG_KERNEL -- cgit v1.1 From 6bfc09e2327dfbffc312004c16188dbf8dfb0297 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 19 Oct 2012 12:49:17 -0700 Subject: rcu: Provide RCU CPU stall warnings for tiny RCU Tiny RCU has historically omitted RCU CPU stall warnings in order to reduce memory requirements, however, lack of these warnings caused Thomas Gleixner some debugging pain recently. Therefore, this commit adds RCU CPU stall warnings to tiny RCU if RCU_TRACE=y. This keeps the memory footprint small, while still enabling CPU stall warnings in kernels built to enable them. Updated to include Josh Triplett's suggested use of RCU_STALL_COMMON config variable to simplify #if expressions. Reported-by: Thomas Gleixner Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- lib/Kconfig.debug | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'lib') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 3a35309..f7329b3 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -970,7 +970,7 @@ config RCU_TORTURE_TEST_RUNNABLE config RCU_CPU_STALL_TIMEOUT int "RCU CPU stall timeout in seconds" - depends on TREE_RCU || TREE_PREEMPT_RCU + depends on RCU_STALL_COMMON range 3 300 default 21 help -- cgit v1.1