On 2014/10/29 16:21, Peter Zijlstra wrote: > On Wed, Oct 29, 2014 at 06:46:03AM +0800, Li, Aubrey wrote: >> 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. > > And work arounds for buggy crap hardware should not be in generic code. > They should be in the platform drivers associated with said crap bugs. > > But I think I see what you're saying, we're going through this dpm_ crap > even for suspend to idle, which is wrong too. > >> 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. > > So you can do cpuidle_resume() before we do the stop machine dance,
I agree, this can leave the current behavior unchanged. I'll send out a refined version soon. > but ideally it'd all be ripped out from generic code and stuffed into > the platform drivers where it belongs. But at the very least it should > be isolated to the S3 path, I bet suspend to disk doesn't care either. > I think this is a good question to Rafael, which I ever asked before. Thanks, -Aubrey -- 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/
