From f99bcb2cdb5843548a2b0b78157cb7a0b4c7ccac Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 2 Jun 2017 11:26:43 -0700 Subject: [PATCH] documentation: Fix relation between nohz_full and rcu_nocbs If a CPU is specified in the nohz_full= kernel boot parameter to a kernel built with CONFIG_NO_HZ_FULL=y, then that CPU's callbacks will be offloaded, just as if that CPU had also been specified in the rcu_nocbs= kernel boot parameter. But the current documentation states that the user must keep these two boot parameters manually synchronized. This commit therefore updates the documentation to reflect reality. Signed-off-by: Paul E. McKenney --- Documentation/admin-guide/kernel-parameters.txt | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index d9c171ce4190..3a99cc96b6b1 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2633,9 +2633,10 @@ In kernels built with CONFIG_NO_HZ_FULL=y, set the specified list of CPUs whose tick will be stopped whenever possible. The boot CPU will be forced outside - the range to maintain the timekeeping. - The CPUs in this range must also be included in the - rcu_nocbs= set. + the range to maintain the timekeeping. Any CPUs + in this list will have their RCU callbacks offloaded, + just as if they had also been called out in the + rcu_nocbs= boot parameter. noiotrap [SH] Disables trapped I/O port accesses.