From: Juri Lelli <juri.lelli@gmail.com>
To: Francisco Jerez <currojerez@riseup.net>
Cc: Javi Merino <Javi.Merino@arm.com>,
linux-pm@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
intel-gfx@lists.freedesktop.org,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Patrick Bellasi <patrick.bellasi@arm.com>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Eero Tamminen <eero.t.tamminen@intel.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>
Subject: Re: [PATCH 0/9] GPU-bound energy efficiency improvements for the intel_pstate driver.
Date: Wed, 11 Apr 2018 19:35:58 +0200 [thread overview]
Message-ID: <20180411173558.GL13334@localhost.localdomain> (raw)
In-Reply-To: <87muy97lr0.fsf@riseup.net>
Hi,
On 11/04/18 09:26, Francisco Jerez wrote:
> Francisco Jerez <currojerez@riseup.net> writes:
>
> > Hi Srinivas,
> >
> > Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> writes:
> >
> >> On Tue, 2018-04-10 at 15:28 -0700, Francisco Jerez wrote:
> >>> Francisco Jerez <currojerez@riseup.net> writes:
> >>>
> >> [...]
> >>
> >>
> >>> For the case anyone is wondering what's going on, Srinivas pointed me
> >>> at
> >>> a larger idle power usage increase off-list, ultimately caused by the
> >>> low-latency heuristic as discussed in the paragraph above. I have a
> >>> v2
> >>> of PATCH 6 that gives the controller a third response curve roughly
> >>> intermediate between the low-latency and low-power states of this
> >>> revision, which avoids the energy usage increase while C0 residency
> >>> is
> >>> low (e.g. during idle) expected for v1. The low-latency behavior of
> >>> this revision is still going to be available based on a heuristic (in
> >>> particular when a realtime-priority task is scheduled). We're
> >>> carrying
> >>> out some additional testing, I'll post the code here eventually.
> >>
> >> Please try sched-util governor also. There is a frequency-invariant
> >> patch, which I can send you (This eventually will be pushed by Peter).
> >> We want to avoid complexity to intel-pstate for non HWP power sensitive
> >> platforms as far as possible.
> >>
> >
> > Unfortunately the schedutil governor (whether frequency invariant or
> > not) has the exact same energy efficiency issues as the present
> > intel_pstate non-HWP governor. Its response is severely underdamped
> > leading to energy-inefficient behavior for any oscillating non-CPU-bound
> > workload. To exacerbate that problem the frequency is maxed out on
> > frequent IO waiting just like the current intel_pstate cpu-load
>
> "just like" here is possibly somewhat unfair to the schedutil governor,
> admittedly its progressive IOWAIT boosting behavior seems somewhat less
> wasteful than the intel_pstate non-HWP governor's IOWAIT boosting
> behavior, but it's still largely unhelpful on IO-bound conditions.
Sorry if I jump in out of the blue, but what you are trying to solve
looks very similar to what IPA [1] is targeting as well. I might be
wrong (I'll try to spend more time reviewing your set), but my first
impression is that we should try to solve similar problems with a more
general approach that could benefit different sys/archs.
I'm Cc-ing some Arm folks...
Best,
- Juri
[1] https://developer.arm.com/open-source/intelligent-power-allocation
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next prev parent reply other threads:[~2018-04-11 17:35 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-28 6:38 [PATCH 0/9] GPU-bound energy efficiency improvements for the intel_pstate driver Francisco Jerez
2018-03-28 6:38 ` [PATCH 1/9] cpufreq: Implement infrastructure keeping track of aggregated IO active time Francisco Jerez
2018-03-28 6:38 ` [PATCH 2/9] Revert "cpufreq: intel_pstate: Replace bxt_funcs with core_funcs" Francisco Jerez
2018-03-28 6:38 ` [PATCH 3/9] Revert "cpufreq: intel_pstate: Shorten a couple of long names" Francisco Jerez
2018-03-28 6:38 ` [PATCH 4/9] Revert "cpufreq: intel_pstate: Simplify intel_pstate_adjust_pstate()" Francisco Jerez
2018-03-28 6:38 ` [PATCH 5/9] Revert "cpufreq: intel_pstate: Drop ->update_util from pstate_funcs" Francisco Jerez
2018-03-28 6:38 ` [PATCH 6/9] cpufreq/intel_pstate: Implement variably low-pass filtering controller for small core Francisco Jerez
2018-03-28 6:38 ` [PATCH 7/9] SQUASH: cpufreq/intel_pstate: Enable LP controller based on ACPI FADT profile Francisco Jerez
2018-03-28 6:38 ` [PATCH 8/9] OPTIONAL: cpufreq/intel_pstate: Expose LP controller parameters via debugfs Francisco Jerez
2018-03-28 6:38 ` [PATCH 9/9] drm/i915/execlists: Report GPU rendering as IO activity to cpufreq Francisco Jerez
2018-03-28 8:02 ` Chris Wilson
2018-03-28 18:55 ` Francisco Jerez
2018-03-28 19:20 ` Chris Wilson
2018-03-28 23:19 ` Chris Wilson
2018-03-29 0:32 ` Francisco Jerez
2018-03-29 1:01 ` Chris Wilson
2018-03-29 1:20 ` Chris Wilson
2018-03-30 18:50 ` [PATCH 0/9] GPU-bound energy efficiency improvements for the intel_pstate driver Francisco Jerez
2018-04-10 22:28 ` Francisco Jerez
2018-04-11 3:14 ` Srinivas Pandruvada
2018-04-11 16:10 ` Francisco Jerez
2018-04-11 16:26 ` Francisco Jerez
2018-04-11 17:35 ` Juri Lelli [this message]
2018-04-12 21:38 ` Francisco Jerez
2018-04-12 6:17 ` Srinivas Pandruvada
2018-04-14 2:00 ` Francisco Jerez
2018-04-14 4:01 ` Srinivas Pandruvada
2018-04-16 14:04 ` Eero Tamminen
2018-04-16 17:27 ` Srinivas Pandruvada
2018-04-12 8:58 ` Peter Zijlstra
2018-04-12 18:34 ` Francisco Jerez
2018-04-12 19:33 ` Peter Zijlstra
2018-04-12 19:55 ` Francisco Jerez
2018-04-13 18:15 ` Peter Zijlstra
2018-04-14 1:57 ` Francisco Jerez
2018-04-14 9:49 ` Peter Zijlstra
2018-04-17 14:03 ` Chris Wilson
2018-04-17 15:34 ` Srinivas Pandruvada
2018-04-17 19:27 ` Francisco Jerez
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