On Monday, May 11, 2020 11:01:41 PM CEST Francisco Jerez wrote: > > --==-=-= > Content-Type: multipart/mixed; boundary="=-=-=" > > --=-=-= > Content-Type: text/plain; charset=utf-8 > Content-Disposition: inline > Content-Transfer-Encoding: quoted-printable > > Peter Zijlstra <peterz@xxxxxxxxxxxxx> writes: > > > On Mon, Apr 27, 2020 at 08:22:47PM -0700, Francisco Jerez wrote: > >> This addresses the technical concerns people brought up about my > >> previous v2 revision of this series. Other than a few bug fixes, the > >> only major change relative to v2 is that the controller is now exposed > >> as a new CPUFREQ generic governor as requested by Rafael (named > >> "adaptive" in this RFC though other naming suggestions are welcome). > >> Main reason for calling this v2.99 rather than v3 is that I haven't > >> yet addressed all the documentation requests from the v2 thread -- > >> Will spend some time doing that as soon as I have an ACK (ideally from > >> Rafael) that things are moving in the right direction. > >>=20 > >> You can also find this series along with the WIP code for non-HWP > >> platforms in this branch: > >>=20 > >> https://github.com/curro/linux/tree/intel_pstate-vlp-v2.99 > >>=20 > >> Thanks! > >>=20 > >> [PATCHv2.99 01/11] PM: QoS: Add CPU_SCALING_RESPONSE global PM QoS limit. > >> [PATCHv2.99 02/11] drm/i915: Adjust PM QoS scaling response frequency ba= > sed on GPU load. > >> [PATCHv2.99 03/11] OPTIONAL: drm/i915: Expose PM QoS control parameters = > via debugfs. > >> [PATCHv2.99 04/11] cpufreq: Define ADAPTIVE frequency governor policy. > >> [PATCHv2.99 05/11] cpufreq: intel_pstate: Reorder intel_pstate_clear_upd= > ate_util_hook() and intel_pstate_set_update_util_hook(). > >> [PATCHv2.99 06/11] cpufreq: intel_pstate: Call intel_pstate_set_update_u= > til_hook() once from the setpolicy hook. > >> [PATCHv2.99 07/11] cpufreq: intel_pstate: Implement VLP controller stati= > stics and target range calculation. > >> [PATCHv2.99 08/11] cpufreq: intel_pstate: Implement VLP controller for H= > WP parts. > >> [PATCHv2.99 09/11] cpufreq: intel_pstate: Enable VLP controller based on= > ACPI FADT profile and CPUID. > >> [PATCHv2.99 10/11] OPTIONAL: cpufreq: intel_pstate: Add tracing of VLP c= > ontroller status. > >> [PATCHv2.99 11/11] OPTIONAL: cpufreq: intel_pstate: Expose VLP controlle= > r parameters via debugfs. > > > > What I'm missing is an explanation for why this isn't using the > > infrastructure that was build for these kinds of things? The thermal > > framework, was AFAIU, supposed to help with these things, and the IPA > > thing in particular is used by ARM to do exactly this GPU/CPU power > > budget thing. > > > > If thermal/IPA is found wanting, why aren't we improving that? > > The GPU/CPU power budget "thing" is only a positive side effect of this > series on some TDP-bound systems. Its ultimate purpose is improving the > energy efficiency of workloads which have a bottleneck on a device other > than the CPU, by giving the bottlenecking device driver some influence > over the response latency of CPUFREQ governors via a PM QoS interface. > This seems to be completely outside the scope of the thermal framework > and IPA AFAIU. > > > > > How much of that ADAPTIVE crud is actually intel_pstate specific? On a > > (really) quick read it appears to me that much of the controller bits > > there can be applied more generic, and thus should not be part of any > > one governor. > > > > The implementation of that is intel_pstate-specific right now, but the > basic algorithm could be made to work on any other governor in > principle, which is why it is exposed as a generic CPUFREQ governor. I > don't care about taking out the generic CPUFREQ governor changes if you > don't like them, and going back to some driver-specific means of turning > it on and off (though Rafael might disagree with that). > > > Specifically, I want to use sched_util as cpufreq governor and use the > > intel_pstate as a passive driver. > > Yeah, getting a similar optimization into the schedutil governor has > been on my wish list for a while, but I haven't had the time to get very > far on that except for a handful of hacks. The intel_pstate handling is > going to be necessary anyway in order to handle HWP systems gracefully, > at least in the near future until schedutil becomes a viable alternative > to intel_pstate in active mode on HWP systems. FWIW, work is under way to make intel_pstate in the passive mode work on HWP systems. I have a prototype patch for that, but it can be improved. I'll post a new version of it for review, possibly next week. Cheers! _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
