On 11/07/2014 08:01 PM, Daniel Lezcano wrote: > When the pmqos latency requirement is set to zero that means "poll in all the > cases". > > That is correctly implemented on x86 but not on the other archs. > > As how is written the code, if the latency request is zero, the governor will > return zero, so corresponding, for x86, to the poll function, but for the > others arch the default idle function. For example, on ARM this is wait-for- > interrupt with a latency of '1', so violating the constraint. > > In order to fix that, do the latency requirement check *before* calling the > cpuidle framework in order to jump to the poll function without entering > cpuidle. That has several benefits: > > 1. It clarifies and unifies the code > 2. It fixes x86 vs other archs behavior > 3. Factors out the call to the same function > 4. Prevent to enter the cpuidle framework with its expensive cost in > calculation > > As the latency_req is needed in all the cases, change the select API to take > the latency_req as parameter in case it is not equal to zero. > > As a positive side effect, it introduces the latency constraint specified > externally, so one more step to the cpuidle/scheduler integration. > > Signed-off-by: Daniel Lezcano <daniel.lezc...@linaro.org> > Acked-by: Nicolas Pitre <n...@linaro.org> > Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org> > Reviewed-by: Len Brown <len.br...@intel.com> > ---
Reviewed-by: Preeti U Murthy <pre...@linux.vnet.ibm.com> Regards Preeti U Murthy -- 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/
