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I needed to add CONFIG_THERMAL / CONFIG_TEGRA_THERM to my kernel. Now the temperatures are accessible via sysfs. Here some numbers during a sbc-bench: (taken while 7-zip was running) /sys/devices/virtual/thermal/thermal_zone3: pllx 51000 /sys/devices/virtual/thermal/thermal_zone1: mem 47000 /sys/devices/virtual/thermal/thermal_zone2: gpu 47000 /sys/devices/virtual/thermal/thermal_zone0: cpu 51000 /sys/class/thermal/thermal_zone3: pllx 51000 /sys/class/thermal/thermal_zone1: mem 47000 /sys/class/thermal/thermal_zone2: gpu 47000 /sys/class/thermal/thermal_zone0: cpu 51000 But reported temperatures during this run seems much lower (cp. http://ix.io/1j4m) I did a watch 'cat /sys/devices/virtual/thermal/thermal_zone0/temp&&cat /sys/class/hwmon/hwmon0/temp1_input' during a sbc-bench and the thermal_zone0 temperature was always between 38 and 53°C while hwmon0 was way lower. And regarding the OPP cpufreq calculation: Now the OPP cpufreq is throttled to ~1565 MHz on the first measurement (no load upfront!), and boosted beyond 2400 MHz on the second OPP calculation at the end of the run. Strange, isn't it? Cpufreq OPP: 204 Measured: 346.544/335.861/346.856 Cpufreq OPP: 306 Measured: 503.798/516.667/515.484 Cpufreq OPP: 408 Measured: 685.631/684.615/676.372 Cpufreq OPP: 510 Measured: 854.971/849.269/856.052 Cpufreq OPP: 612 Measured: 1030.608/1035.536/1035.546 Cpufreq OPP: 714 Measured: 1205.473/1201.910/1202.302 Cpufreq OPP: 816 Measured: 1374.352/1372.307/1375.552 Cpufreq OPP: 918 Measured: 1554.848/1562.581/1555.110 Cpufreq OPP: 1020 Measured: 1721.640/1725.044/1721.787 Cpufreq OPP: 1122 Measured: 1894.246/1895.047/1894.980 Cpufreq OPP: 1224 Measured: 2064.348/2064.053/2065.067 Cpufreq OPP: 1326 Measured: 2238.183/2244.731/2240.394 Cpufreq OPP: 1428 Measured: 2414.822/2414.966/2414.735 Cpufreq OPP: 1530 Measured: 2414.909/2414.533/2415.227 Cpufreq OPP: 1632 Measured: 2415.284/2415.458/2408.336 Cpufreq OPP: 1734 Measured: 2419.049/2408.164/2415.892 Cpufreq OPP: 1836 Measured: 2415.342/2421.255/2414.764 Cpufreq OPP: 1938 Measured: 2408.595/2416.615/2416.442 Cpufreq OPP: 2014 Measured: 2416.702/2411.013/2416.818 Cpufreq OPP: 2116 Measured: 2416.905/2417.339/2408.739 Cpufreq OPP: 2218 Measured: 2417.455/2417.542/2424.252 Cpufreq OPP: 2320 Measured: 2417.513/2410.725/2417.629 This behaviour makes benchmarking not easy... ;-)

Here the result for a Jetson TK1 with more or less mainline kernel 4.14 and Debian Buster (sorry, currently no Stretch available): http://ix.io/1j0f There are some discrepancies in both cpufreq OPP table!? Any idea, how to read those numbers? Never had a stability issue and normally CPU is not a bottleneck for me, so I'm not really worried about throttling. I'm using my Jetsons with the little standard fan, but maybe it's time to enable the temperature sensors somehow :).