Messages in this thread | | | Date | Tue, 09 Feb 2010 09:00:54 -0800 | From | Randy Dunlap <> | Subject | Re: [v11 PATCH 1/9]: cpuidle: Design documentation patch |
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On 02/09/10 00:29, Arun R Bharadwaj wrote: > * Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2010-02-09 13:58:16]: > > This patch adds a little information about the redesigned cpuidle > infrastructure in Documentation/cpuidle/core.txt > > Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com> > --- > Documentation/cpuidle/core.txt | 35 +++++++++++++++++++++++++++++++++++ > 1 file changed, 35 insertions(+) > > Index: linux.trees.git/Documentation/cpuidle/core.txt > =================================================================== > --- linux.trees.git.orig/Documentation/cpuidle/core.txt > +++ linux.trees.git/Documentation/cpuidle/core.txt > @@ -21,3 +21,38 @@ which can be used to switch governors at > is meant for developer testing only. In normal usage, kernel picks the > best governor based on governor ratings. > SEE ALSO: sysfs.txt in this directory. > + > +Design: > + > +Cpuidle allows for registration of multiple sets of idle routines. > +The latest registered set is used by cpuidle governors as the current > +active set to choose the right idle state. This set is managed as a > +list and each time the newly registered set is added to the head of the > +list and made the current active set. > + > +An example of how this would work on x86 is shown below. > + +----------------- ----------------- +| | | | +| choose b/w | mwait is chosen | mwait | +| mwait, poll, |-------------------------------------> |(current active| +| default, c1e | register to cpuidle | set) | +| | with mwait as the idle routine | | +----------------- -----------------
What is "b/w" above? "between"? I've see "btw" used a few times as an abbreviation for between, but I don't recall ever seeing b/w. OTOH, I have seen b/w used for bandwidth.
> + > + > +----------------- ----------------- > +| | | c1, c2, c3 | > +| ACPI | register to cpuidle | (current) | > +| discovery |-------------------------------------> |---------------| > +| | with c1, c2, c3 | mwait | > +| | as set of idle routines | | > +----------------- ----------------- > + > +With this mechanism, a module can register and unregister its set of > +idle routines at run time in a clean manner. > + > +The main idle routine called inside cpu_idle() of every arch is defined in > +driver/cpuidle/cpuidle.c which would in turn call the idle routine selected
drivers/
> +by the governor. If the CONFIG_CPU_IDLE is disabled, the arch needs to > +provide an alternate definition for cpuidle_idle_call().
-- ~Randy
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