On Wed, Sep 23, 2015 at 03:17:59AM +0200, Rafael J. Wysocki wrote: > On Tuesday, September 22, 2015 04:34:19 PM Luiz Capitulino wrote: > > Hi, > > Hi, > > Please always CC patches related to power management to > linux...@vger.kernel.org. > > Also CCing Len Brown who's the maintainer of the intel_idle driver and Peter > Z.
And the sched people for touching kernel/sched (thanks Rafael)! > > Some archs allow the system administrator to set the > > idle thread behavior to spin instead of entering > > sleep states. The x86 arch, for example, has a idle= > > command-line parameter for this purpose. > > > > However, the command-line parameter has two problems: > > > > 1. You have to reboot if you change your mind > > 2. This setting affects all system cores > > > > The second point is relevant for systems where cores > > are partitioned into bookkeeping and low-latency cores. > > Usually, it's OK for bookkeeping cores to enter deeper > > sleep states. It's only the low-latency cores that should > > poll when entering idle. > > This looks like a use case for PM QoS to me rather. You'd need to make it > work per-CPU rather than globally, but that really is about asking for > minimum latency. Agreed, this should very much hook into the PM QoS stuff. > > > This series adds the following file: > > > > /sys/devices/system/cpu/cpu_idle > > > > This file outputs and stores a cpumask of the cores > > which will have idle polling behavior. > > I don't like this interface at all. > > You have a cpuidle directory per core already, so what's the reason to add an Yeah this should very much not be exposed like this. Ideally every cpuidle driver would get 'polling' as a default state and the QoS constraints might select it if nothing else matches. And no mucking about with the force polling flag at _all_. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
