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| author | Paul E. McKenney | 2019-03-06 00:28:19 +0100 |
|---|---|---|
| committer | Paul E. McKenney | 2019-03-26 22:37:49 +0100 |
| commit | da8739f23fadf05809c6c37c327367b229467045 (patch) | |
| tree | 665dafa91dfb5d47e077582d74f562974eea3119 /Documentation/admin-guide/kernel-parameters.txt | |
| parent | rcu: Move common code out of if-else block (diff) | |
| download | kernel-qcow2-linux-da8739f23fadf05809c6c37c327367b229467045.tar.gz kernel-qcow2-linux-da8739f23fadf05809c6c37c327367b229467045.tar.xz kernel-qcow2-linux-da8739f23fadf05809c6c37c327367b229467045.zip | |
rcu: Allow rcu_nocbs= to specify all CPUs
Currently, the rcu_nocbs= kernel boot parameter requires that a specific
list of CPUs be specified, and has no way to say "all of them".
As noted by user RavFX in a comment to Phoronix topic 1002538, this
is an inconvenient side effect of the removal of the RCU_NOCB_CPU_ALL
Kconfig option. This commit therefore enables the rcu_nocbs= kernel boot
parameter to be given the string "all", as in "rcu_nocbs=all" to specify
that all CPUs on the system are to have their RCU callbacks offloaded.
Another approach would be to make cpulist_parse() check for "all", but
there are uses of cpulist_parse() that do other checking, which could
conflict with an "all". This commit therefore focuses on the specific
use of cpulist_parse() in rcu_nocb_setup().
Just a note to other people who would like changes to Linux-kernel RCU:
If you send your requests to me directly, they might get fixed somewhat
faster. RavFX's comment was posted on January 22, 2018 and I first saw
it on March 5, 2019. And the only reason that I found it -at- -all- was
that I was looking for projects using RCU, and my search engine showed
me that Phoronix comment quite by accident. Your choice, though! ;-)
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 2b8ee90bb644..d377a2166b79 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3623,7 +3623,9 @@ see CONFIG_RAS_CEC help text. rcu_nocbs= [KNL] - The argument is a cpu list, as described above. + The argument is a cpu list, as described above, + except that the string "all" can be used to + specify every CPU on the system. In kernels built with CONFIG_RCU_NOCB_CPU=y, set the specified list of CPUs to be no-callback CPUs. |