Messages in this thread | | | Date | Tue, 30 Apr 2013 14:46:12 -0400 | From | Dave Jones <> | Subject | Re: rcu: Provide compile-time control for no-CBs CPUs |
| |
On Tue, Apr 30, 2013 at 03:21:26PM +0000, Linux Kernel wrote:
> +choice > + prompt "Build-forced no-CBs CPUs" > + default RCU_NOCB_CPU_NONE > + help > + This option allows no-CBs CPUs to be specified at build time. > + Additional no-CBs CPUs may be specified by the rcu_nocbs= > + boot parameter. > + > +config RCU_NOCB_CPU_NONE > + bool "No build_forced no-CBs CPUs" > + depends on RCU_NOCB_CPU > + help > + This option does not force any of the CPUs to be no-CBs CPUs. > + Only CPUs designated by the rcu_nocbs= boot parameter will be > + no-CBs CPUs. > + > +config RCU_NOCB_CPU_ZERO > + bool "CPU 0 is a build_forced no-CBs CPU" > + depends on RCU_NOCB_CPU > + help > + This option forces CPU 0 to be a no-CBs CPU. Additional CPUs > + may be designated as no-CBs CPUs using the rcu_nocbs= boot > + parameter will be no-CBs CPUs. > + > + Select this if CPU 0 needs to be a no-CBs CPU for real-time > + or energy-efficiency reasons. > + > +config RCU_NOCB_CPU_ALL > + bool "All CPUs are build_forced no-CBs CPUs" > + depends on RCU_NOCB_CPU > + help > + This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs= > + boot parameter will be ignored. > + > + Select this if all CPUs need to be no-CBs CPUs for real-time > + or energy-efficiency reasons.
Note that entering '?' when prompted in oldconfig only outputs the help parameter from the choice section.
Additionally, nowhere in any of this text does it say what a "no-CB CPU" is, or why I would care, or even what the downsides are for each option.
I nominate this changeset for an award for most obtuse kconfig text in 3.10 (so far)
Dave
| |