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* brocken devfreq simple_ondemand for Odroid XU3/4?
@ 2020-06-23 16:47 ` Willy Wolff
  0 siblings, 0 replies; 50+ messages in thread
From: Willy Wolff @ 2020-06-23 16:47 UTC (permalink / raw)
  To: Chanwoo Choi, MyungJoo Ham, Kyungmin Park, Kukjin Kim,
	Krzysztof Kozlowski, linux-pm, linux-samsung-soc,
	linux-arm-kernel, linux-kernel

Hi everybody,

Is DVFS for memory bus really working on Odroid XU3/4 board?
Using a simple microbenchmark that is doing only memory accesses, memory DVFS
seems to not working properly:

The microbenchmark is doing pointer chasing by following index in an array.
Indices in the array are set to follow a random pattern (cutting prefetcher),
and forcing RAM access.

git clone https://github.com/wwilly/benchmark.git \
  && cd benchmark \
  && source env.sh \
  && ./bench_build.sh \
  && bash source/scripts/test_dvfs_mem.sh

Python 3, cmake and sudo rights are required.

Results:
DVFS CPU with performance governor
mem_gov = simple_ondemand at 165000000 Hz in idle, should be bumped when the
benchmark is running.
- on the LITTLE cluster it takes 4.74308 s to run (683.004 c per memory access),
- on the big cluster it takes 4.76556 s to run (980.343 c per moemory access).

While forcing DVFS memory bus to use performance governor,
mem_gov = performance at 825000000 Hz in idle,
- on the LITTLE cluster it takes 1.1451 s to run (164.894 c per memory access),
- on the big cluster it takes 1.18448 s to run (243.664 c per memory access).

The kernel used is the last 5.7.5 stable with default exynos_defconfig.

Cheers,
Willy

^ permalink raw reply	[flat|nested] 50+ messages in thread

end of thread, other threads:[~2020-07-01 15:49 UTC | newest]

Thread overview: 50+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-23 16:47 brocken devfreq simple_ondemand for Odroid XU3/4? Willy Wolff
2020-06-23 16:47 ` Willy Wolff
2020-06-23 19:02 ` Krzysztof Kozlowski
2020-06-23 19:02   ` Krzysztof Kozlowski
2020-06-23 19:11   ` Krzysztof Kozlowski
2020-06-23 19:11     ` Krzysztof Kozlowski
2020-06-24  8:01     ` Willy Wolff
2020-06-24  8:01       ` Willy Wolff
2020-06-24  8:14       ` Krzysztof Kozlowski
2020-06-24  8:14         ` Krzysztof Kozlowski
2020-06-24  8:52         ` Willy Wolff
2020-06-24  8:52           ` Willy Wolff
2020-06-24 10:32     ` Lukasz Luba
2020-06-24 10:32       ` Lukasz Luba
2020-06-24 11:18       ` Kamil Konieczny
2020-06-24 11:18         ` Kamil Konieczny
2020-06-24 12:06         ` Krzysztof Kozlowski
2020-06-24 12:06           ` Krzysztof Kozlowski
2020-06-24 13:03           ` Lukasz Luba
2020-06-24 13:03             ` Lukasz Luba
2020-06-24 13:13             ` Krzysztof Kozlowski
2020-06-24 13:13               ` Krzysztof Kozlowski
2020-06-24 13:42               ` Lukasz Luba
2020-06-24 13:42                 ` Lukasz Luba
2020-06-24 15:11       ` Sylwester Nawrocki
2020-06-24 15:11         ` Sylwester Nawrocki
2020-06-25 10:02         ` Lukasz Luba
2020-06-25 10:02           ` Lukasz Luba
2020-06-25 11:30           ` Kamil Konieczny
2020-06-25 11:30             ` Kamil Konieczny
2020-06-25 12:02             ` Lukasz Luba
2020-06-25 12:02               ` Lukasz Luba
2020-06-25 12:12               ` Kamil Konieczny
2020-06-25 12:12                 ` Kamil Konieczny
2020-06-26 11:22                 ` Bartlomiej Zolnierkiewicz
2020-06-26 11:22                   ` Bartlomiej Zolnierkiewicz
2020-06-29  1:43                   ` Chanwoo Choi
2020-06-29  1:43                     ` Chanwoo Choi
2020-06-29 11:52                     ` Lukasz Luba
2020-06-29 11:52                       ` Lukasz Luba
2020-07-01 15:48                       ` Willy Wolff
2020-07-01 15:48                         ` Willy Wolff
2020-06-29 11:34                   ` Lukasz Luba
2020-06-29 11:34                     ` Lukasz Luba
2020-06-26 17:50           ` Sylwester Nawrocki
2020-06-26 17:50             ` Sylwester Nawrocki
2020-06-29 11:41             ` Lukasz Luba
2020-06-29 11:41               ` Lukasz Luba
2020-06-29  1:52         ` Chanwoo Choi
2020-06-29  1:52           ` Chanwoo Choi

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