I'm been trying to track down why the USB performance on my BBB's has been abysmal. I've discovered that the default on-demand governor is definitely a major contributor to the slowdown.
Basically, with the ondemand governor, I'm seeing read performance off of a USB3 thumb drive of well under 2MB/sec. In other words, really slow. For example: root@FPP:/home/fpp# uname -a Linux FPP 4.14.60-ti-r67 #1 SMP PREEMPT Sat Aug 4 19:54:06 UTC 2018 armv7l GNU/Linux root@FPP:/home/fpp# cpufreq-set -g ondemand root@FPP:/home/fpp# dd if=/dev/sda1 of=/dev/null bs=1048576 count=32 32+0 records in 32+0 records out 33554432 bytes (34 MB, 32 MiB) copied, 24.9291 s, 1.3 MB/s root@FPP:/home/fpp# dd if=/dev/sda1 of=/dev/null bs=1048576 count=32 32+0 records in 32+0 records out 33554432 bytes (34 MB, 32 MiB) copied, 22.283 s, 1.5 MB/s (yes.. "dd" isn't a great benchmark, but it's trivial to show the issue). Once I switch to the performance governor, things improve quite a bit: root@FPP:/home/fpp# cpufreq-set -g performance root@FPP:/home/fpp# dd if=/dev/sda1 of=/dev/null bs=1048576 count=64 64+0 records in 64+0 records out 67108864 bytes (67 MB, 64 MiB) copied, 6.96759 s, 9.6 MB/s root@FPP:/home/fpp# dd if=/dev/sda1 of=/dev/null bs=1048576 count=64 64+0 records in 64+0 records out 67108864 bytes (67 MB, 64 MiB) copied, 6.98015 s, 9.6 MB/s It's still not anywhere near what a Raspberry Pi is able to do with the same thumb drive (30MB/s), but it's a huge improvement. Is there any setting or anything that can be used to improve the read performance of the USB besides locking the CPU at 1Ghz? -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/70a6d8da-052f-444f-8ef5-7ccb3121a4c5%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
