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authorPaul Gortmaker <paul.gortmaker@windriver.com>2012-12-20 13:19:22 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2013-01-08 14:12:19 -0800
commit1b0048a44c502c5ab850203e6e0a6498d7d8676d (patch)
tree762871009312e2e744ff013921b9ae940e567585 /Documentation
parent353af9c9a866b07492b15a4efd18ec93123d3a1d (diff)
rcu: Make rcu_nocb_poll an early_param instead of module_param
The as-documented rcu_nocb_poll will fail to enable this feature for two reasons. (1) there is an extra "s" in the documented name which is not in the code, and (2) since it uses module_param, it really is expecting a prefix, akin to "rcutree.fanout_leaf" and the prefix isn't documented. However, there are several reasons why we might not want to simply fix the typo and add the prefix: 1) we'd end up with rcutree.rcu_nocb_poll, and rather probably make a change to rcutree.nocb_poll 2) if we did #1, then the prefix wouldn't be consistent with the rcu_nocbs=<cpumap> parameter (i.e. one with, one without prefix) 3) the use of module_param in a header file is less than desired, since it isn't immediately obvious that it will get processed via rcutree.c and get the prefix from that (although use of module_param_named() could clarify that.) 4) the implied export of /sys/module/rcutree/parameters/rcu_nocb_poll data to userspace via module_param() doesn't really buy us anything, as it is read-only and we can tell if it is enabled already without it, since there is a printk at early boot telling us so. In light of all that, just change it from a module_param() to an early_setup() call, and worry about adding it to /sys later on if we decide to allow a dynamic setting of it. Also change the variable to be tagged as read_mostly, since it will only ever be fiddled with at most, once at boot. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/kernel-parameters.txt2
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 363e348bff9..6c723811c0a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2438,7 +2438,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
real-time workloads. It can also improve energy
efficiency for asymmetric multiprocessors.
- rcu_nocbs_poll [KNL,BOOT]
+ rcu_nocb_poll [KNL,BOOT]
Rather than requiring that offloaded CPUs
(specified by rcu_nocbs= above) explicitly
awaken the corresponding "rcuoN" kthreads,