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| author | Joel Fernandes <joel@joelfernandes.org> | 2022-04-22 17:52:47 +0000 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2022-07-19 11:43:34 -0700 |
| commit | b37a667c62421b34e96b05613457b9fb0ed66ea1 (patch) | |
| tree | 759a63f2ea459e38989e2ab0b9bce7cccaa027b6 /Documentation/admin-guide | |
| parent | 3a5761dc025da47960755ac64d9fbf1c32e8cd80 (diff) | |
| download | linux-b37a667c62421b34e96b05613457b9fb0ed66ea1.tar.gz linux-b37a667c62421b34e96b05613457b9fb0ed66ea1.tar.bz2 linux-b37a667c62421b34e96b05613457b9fb0ed66ea1.zip | |
rcu/nocb: Add an option to offload all CPUs on boot
Systems built with CONFIG_RCU_NOCB_CPU=y but booted without either
the rcu_nocbs= or rcu_nohz_full= kernel-boot parameters will not have
callback offloading on any of the CPUs, nor can any of the CPUs be
switched to enable callback offloading at runtime. Although this is
intentional, it would be nice to have a way to offload all the CPUs
without having to make random bootloaders specify either the rcu_nocbs=
or the rcu_nohz_full= kernel-boot parameters.
This commit therefore provides a new CONFIG_RCU_NOCB_CPU_DEFAULT_ALL
Kconfig option that switches the default so as to offload callback
processing on all of the CPUs. This default can still be overridden
using the rcu_nocbs= and rcu_nohz_full= kernel-boot parameters.
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Uladzislau Rezki <urezki@gmail.com>
(In v4.1, fixed issues with CONFIG maze reported by kernel test robot).
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 2522b11e593f..34605c275294 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3659,6 +3659,9 @@ just as if they had also been called out in the rcu_nocbs= boot parameter. + Note that this argument takes precedence over + the CONFIG_RCU_NOCB_CPU_DEFAULT_ALL option. + noiotrap [SH] Disables trapped I/O port accesses. noirqdebug [X86-32] Disables the code which attempts to detect and @@ -4557,6 +4560,9 @@ no-callback mode from boot but the mode may be toggled at runtime via cpusets. + Note that this argument takes precedence over + the CONFIG_RCU_NOCB_CPU_DEFAULT_ALL option. + rcu_nocb_poll [KNL] Rather than requiring that offloaded CPUs (specified by rcu_nocbs= above) explicitly |