Hi! > Hardware C-state auto-demotion is a mechanism where the HW overrides > the OS C-state request, instead demoting to a shallower state, > which is less expensive, but saves less power. > > Modern Linux should generally get exactly the states it requests. > In particular, when a CPU is taken off-line, it must not be demoted, else > it can prevent the entire package from reaching deep C-states. > > https://bugzilla.kernel.org/show_bug.cgi?id=25252 > > > +#define MSR_NHM_SNB_PKG_CST_CFG_CTL 0x000000e2 > +#define NHM_C3_AUTO_DEMOTE (1UL << 25) > +#define NHM_C1_AUTO_DEMOTE (1UL << 26) > + .... > @@ -85,6 +86,12 @@ static int intel_idle(struct cpuidle_dev > static struct cpuidle_state *cpuidle_state_table; > > /* > + * Hardware C-state auto-demotion may not always be optimal. > + * Indicate which enable bits to clear here. > + */ > +static unsigned long long auto_demotion_disable_flags; Why long long here, but long above? -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
