在Ubuntu 17.04中设置Intel GPU限制不再有效

我以前使用过Ubuntu MATE 16.04，但是最近切换到了17.04，因为它附带了更新的Thermald，并且我认为它将为我解决类似的错误。我在Ubuntu 16.04中遇到了散热问题，类似于那里描述的问题，但是考虑到据说它已在Thermald（1.5.4-3）中修复，而Ubuntu 17.04默认带有更新版本，我认为它对我来说会更好总体而言，可能还会在整个系统中进行修复。因此，我已经安装了17.04，并进行了尝试，一切正常，因此我完全迁移了。
过了一会儿，尽管我遇到了一个非常奇怪的问题，即系统完全忽略了设置的CPU限制。在16.04中，只有在Intel GPU试图以与CPU工作状态相关的频率（高于限制）的频率工作时，我才想到。例如，如果我运行：

sudo cat /sys/kernel/debug/dri/1/i915_ring_freq_table

这是我的输出：

GPU freq (MHz)  Effective CPU freq (MHz)    Effective Ring freq (MHz)
650             800                         0
700             800                         0
750             1400                        0
800             1500                        0
850             1600                        0
900             1600                        0
950             1700                        0
1000            1800                        0
1050            1900                        0
1100            2000                        0

因此，如果我希望我的CPU最高工作频率为1500MHz，并且不要再提高了，那就意味着GPU必须限制在800MHz，并且永远不要再提高，因为GPU是集成在CPU中的，因此它们被捆绑在一起。
在Ubuntu 16.04中，我所做的是通过写入/sys/kernel/debug/dri/1/i915_max_freq要成为GPU可以达到的最大限制的值来手动设置GPU限制。当我将CPU限制为1500MHz时，我还将运行：

echo 800 | sudo tee /sys/kernel/debug/dri/1/i915_max_freq  

而且我的GPU将保持在一定范围内，而不会影响CPU的工作频率。
但是，在Ubuntu 17.04中，设置限制后，GPU仍会一直上升到1100MHz，这使任何CPU限制毫无意义，并会使处理器过热。

~$ sudo cat /sys/kernel/debug/dri/1/i915_max_freq
800

如您所见，限制已设置并就位。现在我们检查frequency_info：

~$ sudo cat /sys/kernel/debug/dri/1/i915_frequency_info
PM IER=0x00000070 IMR=0xffffff8f ISR=0x00000000 IIR=0x00000000, MASK=0x0000002a
pm_intr_keep: 0x00000004
GT_PERF_STATUS: 0x000016cb
Render p-state ratio: 22
Render p-state VID: 203
Render p-state limit: 255
RPSTAT1: 0x00041610
RPMODECTL: 0x00000d92
RPINCLIMIT: 0x000019fa
RPDECLIMIT: 0x00003a98
RPNSWREQ: 1100MHz
CAGF: 1100MHz
RP CUR UP EI: 7165 (9171us)
RP CUR UP: 7006 (8967us)
RP PREV UP: 6725 (8608us)
Up threshold: 85%
RP CUR DOWN EI: 1314 (1681us)
RP CUR DOWN: 1315 (1683us)
RP PREV DOWN: 23741 (30388us)
Down threshold: 60%
Lowest (RPN) frequency: 650MHz
Nominal (RP1) frequency: 650MHz
Max non-overclocked (RP0) frequency: 1100MHz
Max overclocked frequency: 1100MHz
Current freq: 1100 MHz
Actual freq: 1100 MHz
Idle freq: 650 MHz
Min freq: 650 MHz
Boost freq: 1100 MHz
Max freq: 1100 MHz
efficient (RPe) frequency: 650 MHz
Current CD clock frequency: 400000 kHz
Max CD clock frequency: 400000 kHz
Max pixel clock frequency: 360000 kHz

我们可以看到电流和实际频率最大为1100MHz。
这还会增加CPU频率忽略的限制，因为如果GPU升高到如此之高，CPU不会降低：

~$ sudo cpufreq-info 
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to [email protected], please.
analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 2.00 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 1.50 GHz and 1.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 2.00 GHz (asserted by call to hardware).
analyzing CPU 1:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 1
  CPUs which need to have their frequency coordinated by software: 1
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 2.00 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 1.50 GHz and 1.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 2.00 GHz (asserted by call to hardware).

如您所见，策略的范围是1.50 GHz到1.50 GHz，但是由于GPU的缘故，它被提高到了最大值。

关闭图形应用程序后：

sudo cat /sys/kernel/debug/dri/1/i915_frequency_info
PM IER=0x00000070 IMR=0xffffff8f ISR=0x00000000 IIR=0x00000000,
[...]
CAGF: 650MHz
[...]
Lowest (RPN) frequency: 650MHz
Nominal (RP1) frequency: 650MHz
Max non-overclocked (RP0) frequency: 1100MHz
Max overclocked frequency: 1100MHz
Current freq: 650 MHz
Actual freq: 650 MHz
Idle freq: 650 MHz
Min freq: 650 MHz
Boost freq: 1100 MHz
Max freq: 1100 MHz
[...]

GPU恢复到最小值，CPU现在可以在分配的限制下工作：

sudo cpufreq-info 
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to [email protected], please.
analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 2.00 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 1.50 GHz and 1.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 1.12 GHz (asserted by call to hardware).
analyzing CPU 1:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 1
  CPUs which need to have their frequency coordinated by software: 1
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 2.00 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 1.50 GHz and 1.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 1.49 GHz (asserted by call to hardware).

问题：如何使intel GPU遵循Ubuntu 17.04中的设置限制，以使其不再混乱我的CPU限制，为什么它忽略在16.04中可用的限制？

更新：经过一番摸索，我发现了这个东西：

sudo cat /sys/kernel/debug/dri/0/i915_rps_boost_info
RPS enabled? 1
GPU busy? yes [1 requests]
CPU waiting? 0
Frequency requested 650
  min hard:650, soft:650; max soft:700, hard:1100
  idle:650, efficient:650, boost:1100
Xorg [1221]: 591 boosts
Kernel (anonymous) boosts: 8
RPS Autotuning (current "low power" window):
  Avg. up: 0% [above threshold? 95%]
  Avg. down: 0% [below threshold? 85%]  

这是什么“ RPS”，难道是GPU助推器最大程度地忽略设置限制的原因吗？