diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/RCU/stallwarn.rst | 11 | ||||
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 4 | ||||
| -rw-r--r-- | Documentation/timers/no_hz.rst | 10 |
3 files changed, 3 insertions, 22 deletions
diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.rst index 28f8ad16db25..78404625bad2 100644 --- a/Documentation/RCU/stallwarn.rst +++ b/Documentation/RCU/stallwarn.rst @@ -254,17 +254,6 @@ period (in this case 2603), the grace-period sequence number (7075), and an estimate of the total number of RCU callbacks queued across all CPUs (625 in this case). -In kernels with CONFIG_RCU_FAST_NO_HZ, more information is printed -for each CPU:: - - 0: (64628 ticks this GP) idle=dd5/3fffffffffffffff/0 softirq=82/543 last_accelerate: a345/d342 dyntick_enabled: 1 - -The "last_accelerate:" prints the low-order 16 bits (in hex) of the -jiffies counter when this CPU last invoked rcu_try_advance_all_cbs() -from rcu_needs_cpu() or last invoked rcu_accelerate_cbs() from -rcu_prepare_for_idle(). "dyntick_enabled: 1" indicates that dyntick-idle -processing is enabled. - If the grace period ends just as the stall warning starts printing, there will be a spurious stall-warning message, which will include the following:: diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 9725c546a0d4..36b83a47e54a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4489,10 +4489,6 @@ on rcutree.qhimark at boot time and to zero to disable more aggressive help enlistment. - rcutree.rcu_idle_gp_delay= [KNL] - Set wakeup interval for idle CPUs that have - RCU callbacks (RCU_FAST_NO_HZ=y). - rcutree.rcu_kick_kthreads= [KNL] Cause the grace-period kthread to get an extra wake_up() if it sleeps three times longer than diff --git a/Documentation/timers/no_hz.rst b/Documentation/timers/no_hz.rst index 20ad23a6c618..f8786be15183 100644 --- a/Documentation/timers/no_hz.rst +++ b/Documentation/timers/no_hz.rst @@ -184,16 +184,12 @@ There are situations in which idle CPUs cannot be permitted to enter either dyntick-idle mode or adaptive-tick mode, the most common being when that CPU has RCU callbacks pending. -The CONFIG_RCU_FAST_NO_HZ=y Kconfig option may be used to cause such CPUs -to enter dyntick-idle mode or adaptive-tick mode anyway. In this case, -a timer will awaken these CPUs every four jiffies in order to ensure -that the RCU callbacks are processed in a timely fashion. - -Another approach is to offload RCU callback processing to "rcuo" kthreads +Avoid this by offloading RCU callback processing to "rcuo" kthreads using the CONFIG_RCU_NOCB_CPU=y Kconfig option. The specific CPUs to 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. +"1,3-5" selects CPUs 1, 3, 4, and 5. Note that CPUs specified by +the "nohz_full" kernel boot parameter are also offloaded. The offloaded CPUs will never queue RCU callbacks, and therefore RCU never prevents offloaded CPUs from entering either dyntick-idle mode |