Messages in this thread | | | Date | Thu, 24 Mar 2011 22:22:00 +0530 | From | Vaidyanathan Srinivasan <> | Subject | Re: [RFC PATCH V4 2/5] cpuidle: list based cpuidle driver registration and selection |
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* Trinabh Gupta <trinabh@linux.vnet.ibm.com> [2011-03-24 19:43:43]:
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> >>But we also have to replace the functionality provided by pm_idle, > >>i.e. call default_idle for platforms where no better idle routine > >>exists, call mwait for pre-nehalem platforms, use intel_idle or > >>acpi_idle for nehalem architectures etc. To manage all this > >>we need a registration mechanism which is conveniently provided > >>by cpuidle. > > > >It isn't immediately clear to me that all of these options > >need to be preserved. > > So what do you suggest can be removed?
Can we use safe_halt() until intel_idle/acpi_idle take over? But what if they do not take over? If safe_halt() is not very bad compared to the variants like mwait_idle and c1e_idle, then we can remove the old code and no need to move them to default driver.
> >Are we suggesting that x86 must always build with cpuidle? > >I'm sure that somebody someplace will object to that. > > Arjan argued that since almost everyone today runs cpuidle > it may be best to include it in the kernel > (https://lkml.org/lkml/2010/10/20/243). But yes, we agreed > that we would have to make cpuidle lighter incrementally. > Making ladder governor optional could be one way for example. > > > >OTOH, if cpuidle is included, I'd like to see the > >non-cpuidle code excluded, since nobody will run it...
The non-cpuidle code will be the select_idle_routine() and related function that cam move to default_driver that register to cpuidle. We can load on-demand as module if better routines fail to register. Maybe we don't need this at all as discussed in the above point?
--Vaidy
[snip]
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