On 15/05/2015 06:16, Viresh Kumar wrote: > On 14-05-15, 16:48, Mason wrote: > >> How do I run the TWD in one-shot mode? > > I haven't refreshed my memory for the earlier reply, but I have tried > to go through the code again. > > The logic is this: > - Oneshot mode is only useful if we are going to support NO_HZ mode. > i.e. we can disable the clkevt device during CPU idle .. > - For that to work, or in other words for the CPU to wake up from the > idle state, we need a broadcast timer. Which will wake up the idle > cpu and its clkevt device. > > You don't have this 'broadcast' timer in your case and so we aren't > able to switch to oneshot mode. > > Even if you do that, you will be stuck in LOW resolution mode. And > so you probably leave this timer as is and use a out-of-CPU-domain > timer for this work, which can support high resolution mode. For the record, my kernel config contains: (There are some BROADCAST-related options enabled.) # # IRQ subsystem # CONFIG_GENERIC_IRQ_PROBE=y CONFIG_GENERIC_IRQ_SHOW=y CONFIG_HARDIRQS_SW_RESEND=y CONFIG_IRQ_DOMAIN=y # CONFIG_IRQ_DOMAIN_DEBUG is not set CONFIG_IRQ_FORCED_THREADING=y CONFIG_KTIME_SCALAR=y CONFIG_GENERIC_CLOCKEVENTS=y CONFIG_GENERIC_CLOCKEVENTS_BUILD=y CONFIG_ARCH_HAS_TICK_BROADCAST=y CONFIG_GENERIC_CLOCKEVENTS_BROADCAST=y # # Timers subsystem # CONFIG_TICK_ONESHOT=y CONFIG_NO_HZ_COMMON=y # CONFIG_HZ_PERIODIC is not set CONFIG_NO_HZ_IDLE=y # CONFIG_NO_HZ_FULL is not set CONFIG_NO_HZ=y CONFIG_HIGH_RES_TIMERS=y # # CPU/Task time and stats accounting # CONFIG_TICK_CPU_ACCOUNTING=y # CONFIG_VIRT_CPU_ACCOUNTING_GEN is not set # CONFIG_IRQ_TIME_ACCOUNTING is not set # CONFIG_BSD_PROCESS_ACCT is not set # CONFIG_TASKSTATS is not set Full config (and platform patch) provided in <555380F8.5050306@xxxxxxx> http://article.gmane.org/gmane.linux.power-management.general/60164 Regards. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
