rcu: Eliminate NOCBs CPU-state Kconfig options

[linux-2.6-block.git] / Documentation / timers / NO_HZ.txt

diff --git a/Documentation/timers/NO_HZ.txt b/Documentation/timers/NO_HZ.txt
index 6eaf576294f3bbd0d4d7d992fc17522edc723d48..2dcaf9adb7a75d3e80ced6dd7edab52a0c181915 100644 (file)
--- a/Documentation/timers/NO_HZ.txt
+++ b/Documentation/timers/NO_HZ.txt
@@ -194,32 +194,9 @@ that the RCU callbacks are processed in a timely fashion.
 
 Another approach is to offload RCU callback processing to "rcuo" kthreads
 using the CONFIG_RCU_NOCB_CPU=y Kconfig option.  The specific CPUs to
-offload may be selected via several methods:
-
-1.     One of three mutually exclusive Kconfig options specify a
-       build-time default for the CPUs to offload:
-
-       a.      The CONFIG_RCU_NOCB_CPU_NONE=y Kconfig option results in
-               no CPUs being offloaded.
-
-       b.      The CONFIG_RCU_NOCB_CPU_ZERO=y Kconfig option causes
-               CPU 0 to be offloaded.
-
-       c.      The CONFIG_RCU_NOCB_CPU_ALL=y Kconfig option causes all
-               CPUs to be offloaded.  Note that the callbacks will be
-               offloaded to "rcuo" kthreads, and that those kthreads
-               will in fact run on some CPU.  However, this approach
-               gives fine-grained control on exactly which CPUs the
-               callbacks run on, along with their scheduling priority
-               (including the default of SCHED_OTHER), and it further
-               allows this control to be varied dynamically at runtime.
-
-2.     The "rcu_nocbs=" kernel boot parameter, which takes a comma-separated
-       list of CPUs and CPU ranges, for example, "1,3-5" selects CPUs 1,
-       3, 4, and 5.  The specified CPUs will be offloaded in addition to
-       any CPUs specified as offloaded by CONFIG_RCU_NOCB_CPU_ZERO=y or
-       CONFIG_RCU_NOCB_CPU_ALL=y.  This means that the "rcu_nocbs=" boot
-       parameter has no effect for kernels built with RCU_NOCB_CPU_ALL=y.
+offload may be selected using The "rcu_nocbs=" kernel boot parameter,
+which takes a comma-separated list of CPUs and CPU ranges, for example,
+"1,3-5" selects CPUs 1, 3, 4, and 5.
 
 The offloaded CPUs will never queue RCU callbacks, and therefore RCU
 never prevents offloaded CPUs from entering either dyntick-idle mode