[Intel-gfx] [TGL-U][iGFX] Monitoring the freq of iGFX with kernel 5.10 on TGL-U i5-1145GRE

[Souza, Jose]

On Mon, 2022-01-10 at 18:56 +0000, Schweikhardt, Markus wrote:
> Hi all,
>  
> I would like to monitor the frequency of the iGPU of my TGL platform while running glmark2 in bursts which means glmark2 is 5secrunning and 5sec not
> running.I disabled RC6 by echo 0 > /sys/class/drm/card0/gt_rc6_enable for my tests. Furthermore, I tried to lock the iGPU frequency to min, RP0 or
> RP1 by setting e.g. 

Maybe is because you are running a old kerne but recent ones have /sys/class/drm/card0/power/rc6_enable that is read-only.
There is no parameter to disable RC6 but you can change the i915 code to not enabled it and run your tests.

> echo 1300 > /sys/class/drm/card0/gt_min_freq_mhz
> echo 1300 > /sys/class/drm/card0/gt_max_freq_mhz
> echo 1300 > /sys/class/drm/card0/gt_boost_freq_mhz.
>  
> For frequency monitoring I am using intel_gpu_top and/sys/class/drm/card0/gt_cur_freq_mhz. I am a bit confused if I compare the output
> becauseintel_gpu_top and/sys/class/drm/card0/gt_cur_freq_mhzshow different results.
> These are my results if I lock gpu Frequency to 1300MHz
>  
> ### /sys/class/drm/card0/gt_cur_freq_mhz
> Every 0.1s: cat
> /sys/class/drm/card0/gt_cur_freq_mhz                                                                                                      node4-
> tglu-rvp: Mon Jan 10 20:22:59 2022
>  
> 1300
>  
> ### intel_gpu_top
> root at node4-tglu-rvp:~/fGvPOC# intel_gpu_top -l
> Freq MHz      IRQ RC6           RCS/0           BCS/0           VCS/0           VCS/1          VECS/0
> req  act       /s   %       %  se  wa       %  se  wa       %  se  wa       %  se  wa       %  se  wa
>    0    0       15 100    0.08   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
>    0    0       16 100    0.08   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
>    0    0       10 100    0.05   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
> 188  172     6045  86   13.22   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
> 1300 1189    44907   0   99.25   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
> 1300 1201    44702   0   99.05   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
> 1300 1182    44873   0   99.23   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
> 1300 1193    44830   0   99.08   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
> 1066  988    36336  19   80.24   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
>    6    6       10 100    0.05   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
>   13   13       15 100    0.08   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
>   13   13       16 100    0.08   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
>    0    0       13 100    0.05   0   0    0.00   0   0    0.00   0   0    0.00   0   0    0.00   0   0
>  
> Can someone help me to understand why /sys/class/drm/card0/gt_cur_freq_mhz always shows 1300MHz and intel_gpu_top (req and act)is dropping to almost
> 0Hz when glmark2 is not running?
> My final goal is to figure out if render p-state transitions can impact the timeliness of my real-time workload running on a RT core.
>  
> Kernel Info:
> Linux node4-tglu-rvp 5.10.41-rt42-intel-ese-standard-lts-rt #1 SMP PREEMPT_RT Thu Sep 23 10:21:35 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
> Intel Yocto BKC MR3
>  
> Thx, Markus
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