diff options
Diffstat (limited to 'Documentation/RCU')
| -rw-r--r-- | Documentation/RCU/rcu.txt | 4 | ||||
| -rw-r--r-- | Documentation/RCU/stallwarn.txt | 14 | ||||
| -rw-r--r-- | Documentation/RCU/trace.txt | 4 | ||||
| -rw-r--r-- | Documentation/RCU/whatisRCU.txt | 2 |
4 files changed, 9 insertions, 15 deletions
diff --git a/Documentation/RCU/rcu.txt b/Documentation/RCU/rcu.txt index bf778332a28f..745f429fda79 100644 --- a/Documentation/RCU/rcu.txt +++ b/Documentation/RCU/rcu.txt @@ -36,7 +36,7 @@ o How can the updater tell when a grace period has completed executed in user mode, or executed in the idle loop, we can safely free up that item. - Preemptible variants of RCU (CONFIG_TREE_PREEMPT_RCU) get the + Preemptible variants of RCU (CONFIG_PREEMPT_RCU) get the same effect, but require that the readers manipulate CPU-local counters. These counters allow limited types of blocking within RCU read-side critical sections. SRCU also uses CPU-local @@ -81,7 +81,7 @@ o I hear that RCU is patented? What is with that? o I hear that RCU needs work in order to support realtime kernels? This work is largely completed. Realtime-friendly RCU can be - enabled via the CONFIG_TREE_PREEMPT_RCU kernel configuration + enabled via the CONFIG_PREEMPT_RCU kernel configuration parameter. However, work is in progress for enabling priority boosting of preempted RCU read-side critical sections. This is needed if you have CPU-bound realtime threads. diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index ef5a2fd4ff70..ed186a902d31 100644 --- a/Documentation/RCU/stallwarn.txt +++ b/Documentation/RCU/stallwarn.txt @@ -26,12 +26,6 @@ CONFIG_RCU_CPU_STALL_TIMEOUT Stall-warning messages may be enabled and disabled completely via /sys/module/rcupdate/parameters/rcu_cpu_stall_suppress. -CONFIG_RCU_CPU_STALL_VERBOSE - - This kernel configuration parameter causes the stall warning to - also dump the stacks of any tasks that are blocking the current - RCU-preempt grace period. - CONFIG_RCU_CPU_STALL_INFO This kernel configuration parameter causes the stall warning to @@ -77,7 +71,7 @@ This message indicates that CPU 5 detected that it was causing a stall, and that the stall was affecting RCU-sched. This message will normally be followed by a stack dump of the offending CPU. On TREE_RCU kernel builds, RCU and RCU-sched are implemented by the same underlying mechanism, -while on TREE_PREEMPT_RCU kernel builds, RCU is instead implemented +while on PREEMPT_RCU kernel builds, RCU is instead implemented by rcu_preempt_state. On the other hand, if the offending CPU fails to print out a stall-warning @@ -89,7 +83,7 @@ INFO: rcu_bh_state detected stalls on CPUs/tasks: { 3 5 } (detected by 2, 2502 j This message indicates that CPU 2 detected that CPUs 3 and 5 were both causing stalls, and that the stall was affecting RCU-bh. This message will normally be followed by stack dumps for each CPU. Please note that -TREE_PREEMPT_RCU builds can be stalled by tasks as well as by CPUs, +PREEMPT_RCU builds can be stalled by tasks as well as by CPUs, and that the tasks will be indicated by PID, for example, "P3421". It is even possible for a rcu_preempt_state stall to be caused by both CPUs -and- tasks, in which case the offending CPUs and tasks will all @@ -205,10 +199,10 @@ o A CPU-bound real-time task in a CONFIG_PREEMPT kernel, which might o A CPU-bound real-time task in a CONFIG_PREEMPT_RT kernel that is running at a higher priority than the RCU softirq threads. This will prevent RCU callbacks from ever being invoked, - and in a CONFIG_TREE_PREEMPT_RCU kernel will further prevent + and in a CONFIG_PREEMPT_RCU kernel will further prevent RCU grace periods from ever completing. Either way, the system will eventually run out of memory and hang. In the - CONFIG_TREE_PREEMPT_RCU case, you might see stall-warning + CONFIG_PREEMPT_RCU case, you might see stall-warning messages. o A hardware or software issue shuts off the scheduler-clock diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 910870b15acd..b63b9bb3bc0c 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -8,7 +8,7 @@ The following sections describe the debugfs files and formats, first for rcutree and next for rcutiny. -CONFIG_TREE_RCU and CONFIG_TREE_PREEMPT_RCU debugfs Files and Formats +CONFIG_TREE_RCU and CONFIG_PREEMPT_RCU debugfs Files and Formats These implementations of RCU provide several debugfs directories under the top-level directory "rcu": @@ -18,7 +18,7 @@ rcu/rcu_preempt rcu/rcu_sched Each directory contains files for the corresponding flavor of RCU. -Note that rcu/rcu_preempt is only present for CONFIG_TREE_PREEMPT_RCU. +Note that rcu/rcu_preempt is only present for CONFIG_PREEMPT_RCU. For CONFIG_TREE_RCU, the RCU flavor maps onto the RCU-sched flavor, so that activity for both appears in rcu/rcu_sched. diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index e48c57f1943b..88dfce182f66 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -137,7 +137,7 @@ rcu_read_lock() Used by a reader to inform the reclaimer that the reader is entering an RCU read-side critical section. It is illegal to block while in an RCU read-side critical section, though - kernels built with CONFIG_TREE_PREEMPT_RCU can preempt RCU + kernels built with CONFIG_PREEMPT_RCU can preempt RCU read-side critical sections. Any RCU-protected data structure accessed during an RCU read-side critical section is guaranteed to remain unreclaimed for the full duration of that critical section. |