On 2014/10/28 16:29, Peter Zijlstra wrote: > On Tue, Oct 28, 2014 at 12:32:16PM +0800, Li, Aubrey wrote: >> On 2014/10/27 15:28, Peter Zijlstra wrote: >>> On Mon, Oct 27, 2014 at 02:27:27PM +0800, Li, Aubrey wrote: >>>>> Now I suppose the problem is with cpu_pause() which needs IPIs to >>>>> complete? Do we really need cpuidle_pause() there? >>>>> cpuidle_uninstall_handlers() seems like a daft thing to call just about >>>>> there. >>>> >>>> Please check the log of 8651f97bd951d0bb1c10fa24e3fa3455193f3548. >>>> Rafael should know more this question than me. >>> >>> That changelog explains its complete bollocks to do it here. We _want_ >>> to enter and/or remain in deep idle states. >> >> cpuidle_resume() will be called at the end of dpm_resume_noirq(). So we >> still are able to enter deep idle states after resume. > > cpuidle_resume is absolute crap, as is cpuidle_suspend for that matter > -- in this case. > > The only reason we needed cpuidle_suspend is because some BIOS shat its > pants when some CPUs were in higher C states while trying to do the S3 > thing. We're not going to use S states or BIOS calls _at_all_, so no > point in kicking CPUs out of their deep C states.
We already kicked CPUs out of their deep C states in dpm_suspend_noirq(). We pause cpuidle in dpm_suspend_noirq() and resume cpuidle in dpm_resume_noirq(), so currently we can't enter deep c-state during S states. That's an intention for some buggy BIOS. However, for freeze state, there is another intention that we want always to enter the *deepest* c-state every time we enter freeze. So we need cpuidle_resume() to make sure we have deep cstate in freeze. So back to your question in another email, > I think you can simply remove them altogether, they're nonsense. We need them to resume cpuidle in freeze. Thanks, -Aubrey > > Read that changelog you referred me to again. > -- > 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/ > > -- 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/
