> >-----Original Message----- > >From: Dave Jones [mailto:davej@xxxxxxxxxx] > >On Thu, Mar 04, 2010 at 03:14:56PM -0800, Venki Pallipadi wrote: > > > > > + if (!strncmp(gov->name, "performance", strlen("performance"))) > > > + epb_val = ENERGY_PERF_BIAS_PERF; > > > + else if (!strncmp(gov->name, "powersave", strlen("powersave"))) > > > + epb_val = ENERGY_PERF_BIAS_POWER; > > > + else > > > + epb_val = ENERGY_PERF_BIAS_ONDEMAND; > > > + > > > + set_epb_on_cpu(epb_val, cpu); > > > + return 0; > > > >hardcoding a list of cpufreq governors is kinda icky, but I don't have > >a better solution. We'll just have to be mindful of it if we ever > >get around to finally making performance/powersave personalities > >of ondemand as was discussed years ago. > > Yes. In that case we will have to find some other way to tie this to > user preference. Lets cross that bridge when we come to it. > >What if the governor is set to 'userspace' ? > >powernowd/cpufreqd are sort of ondemand-done-in-userspace, but there > >may also be other userspace governors we don't know about. > >I suppose it's not catastrophic.. > > Userspace/ondemand/conservative can all be at middle ground here as > they are mostly used where user expects adaptive kind of behaviour. Frankly, if somebody cares about power or performance, they shouldn't be running powernowd/cpufreqd, and so they should be blissfully ignorant and satisfied with the default, which is 'balanced'. > I did think about exporting this as a new tunable in /sys and let > userspace deal with it. But, that doesn't help with having sane default > values and users (background apps) may shoot themselves in the foot > with it. We really do need a central place for userspace to communicate power/performance bias policy to the kernel -- and for kernel drivers of all types to pick up that policy. I think that ideally the sysfs interface should be generic, and that on systems with this MSR, the MSR gets plugged into updates to that generic interface. I think that this driver exposing the MSR to cpufreq is useful, but perhaps it is just a stepping stone to the generic I/F that we really should implement... Len Brown, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
