Messages in this thread | | | Date | Fri, 12 Feb 2021 00:44:45 +0100 | From | Pali Rohár <> | Subject | Re: [PATCH mvebu v2 00/10] Armada 37xx: Fix cpufreq changing base CPU speed to 800 MHz from 1000 MHz |
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On Thursday 11 February 2021 12:22:52 nnet wrote: > On Thu, Feb 11, 2021, at 11:55 AM, Pali Rohár wrote: > > On Wednesday 10 February 2021 11:08:59 nnet wrote: > > > On Wed, Feb 10, 2021, at 10:03 AM, Pali Rohár wrote: > > > > > > Hello! Could you please enable userspace governor during kernel > > > > > > compilation? > > > > > > > > > > > > CONFIG_CPU_FREQ_GOV_USERSPACE=y > > > > > > > > > > > > It can be activated via command: > > > > > > > > > > > > echo userspace > /sys/devices/system/cpu/cpufreq/policy0/scaling_governor > > > > > > > > > > > > After that you can "force" CPU frequency to specific value, e.g.: > > > > > > > > > > > > echo 1000000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed > > > > > > > > > > > > I need to know which switch (from --> to freq) cause this system hang. > > > > > > > > > > > > This patch series (via MIN_VOLT_MV_FOR_L0_L1_1GHZ) is fixing only > > > > > > switching from 500 MHz to 1000 MHz on 1 GHz variant. As only this switch > > > > > > is causing issue. > > > > > > > > > > > > I have used following simple bash script to check that switching between > > > > > > 500 MHz and 1 GHz is stable: > > > > > > > > > > > > while true; do > > > > > > echo 1000000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed; > > > > > > echo 500000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed; > > > > > > echo 1000000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed; > > > > > > echo 500000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed; > > > > > > done > > > > > > > > > > echo userspace | tee /sys/devices/system/cpu/cpufreq/policy0/scaling_governor > > > > > while true; do > > > > > echo 1200000 | tee /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed; > > > > > echo 600000 | tee /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed; > > > > > done > > > > > > > > > > >> +#define MIN_VOLT_MV_FOR_L0_L1_1GHZ 1108 > > > > > > > > > > With 1108 I get a freeze within a minute. The last output to stdout is 600000. > > > > > > > > > > With 1120 it takes a few minutes. > > > > > > > > > > With any of 1225, 1155, 1132 the device doesn't freeze over the full 5 minute load test. > > > > > > > > > > I'm using ondemand now with the above at 1132 without issue so far. > > > > > > > > Great, thank you for testing! > > > > > > > > Can you check if switching between any two lower frequencies 200000 > > > > 300000 600000 is stable? > > > > > > This is stable using 1132 mV for MIN_VOLT_MV_FOR_L0_L1_1GHZ: > > > > > > while true; do > > > # down > > > echo 1200000 | tee /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed; > > ... > > > > Hello! > > > > Could you please re-run test without tee, in form as I have shown above? > > UART is slow and printing something to console adds delay which decrease > > probability that real issue is triggered as this is timing issue. > > The test was done over SSH.
Ok! But it is still better to not print any results as it adds unwanted delay between frequency switching.
> > Also please do tests just between two frequencies in loop as I observed > > that switching between more decreased probability to hit issue. > > > > > > echo userspace | tee /sys/devices/system/cpu/cpufreq/policy0/scaling_governor > > > > > while true; do > > > > > echo 1200000 | tee /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed; > > > > > echo 600000 | tee /sys/devices/system/cpu/cpufreq/policy0/scaling_setspeed; > > > > > done > > The first test ^ switched between 600 MHz and 1.2 GHz. > > > The real issue for 1 GHz variant of A3720 is only when doing switch from > > 500 MHz to 1 GHz. So could you try to do some tests also without > > changing MIN_VOLT_MV_FOR_L0_L1_1GHZ and switching just between non-1.2 > > frequencies (to verify that on 1.2 GHz variant it is also from 600 MHz > > to 1.2 GHz)? > > With 1108 mV and switching between 600 MHz and 1.2GHz, I always saw a freeze within a minute.
I mean to try switching with 1.108 V between 200 MHz and 300 MHz or between 300 MHz and 600 MHz. To check that issue is really only with switch from 600 MHz to 1.2 GHz.
I need to know if current settings are fine for 200, 300 and 600 MHz frequencies and the only 600 --> 1200 needs to be fixed.
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