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authorMauro Carvalho Chehab <mchehab@s-opensource.com>2017-07-17 11:17:36 -0300
committerMauro Carvalho Chehab <mchehab@s-opensource.com>2017-07-17 11:17:36 -0300
commita3db9d60a118571e696b684a6e8c692a2b064941 (patch)
treeff7bae0f79b7a2ee0bce03de4f883550200c52a9 /Documentation/timers/NO_HZ.txt
parentmedia: staging: cxd2099: Activate cxd2099 buffer mode (diff)
parentLinux v4.13-rc1 (diff)
downloadlinux-dev-a3db9d60a118571e696b684a6e8c692a2b064941.tar.xz
linux-dev-a3db9d60a118571e696b684a6e8c692a2b064941.zip
Merge tag 'v4.13-rc1' into patchwork
Linux v4.13-rc1 * tag 'v4.13-rc1': (11136 commits) Linux v4.13-rc1 random: reorder READ_ONCE() in get_random_uXX random: suppress spammy warnings about unseeded randomness replace incorrect strscpy use in FORTIFY_SOURCE kmod: throttle kmod thread limit kmod: add test driver to stress test the module loader MAINTAINERS: give kmod some maintainer love xtensa: use generic fb.h fault-inject: add /proc/<pid>/fail-nth fault-inject: simplify access check for fail-nth fault-inject: make fail-nth read/write interface symmetric fault-inject: parse as natural 1-based value for fail-nth write interface fault-inject: automatically detect the number base for fail-nth write interface kernel/watchdog.c: use better pr_fmt prefix MAINTAINERS: move the befs tree to kernel.org lib/atomic64_test.c: add a test that atomic64_inc_not_zero() returns an int mm: fix overflow check in expand_upwards() ubifs: Set double hash cookie also for RENAME_EXCHANGE ubifs: Massage assert in ubifs_xattr_set() wrt. init_xattrs ubifs: Don't leak kernel memory to the MTD ...
Diffstat (limited to 'Documentation/timers/NO_HZ.txt')
-rw-r--r--Documentation/timers/NO_HZ.txt29
1 files changed, 3 insertions, 26 deletions
diff --git a/Documentation/timers/NO_HZ.txt b/Documentation/timers/NO_HZ.txt
index 6eaf576294f3..2dcaf9adb7a7 100644
--- 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