[Edited] I am using the grinch kernel
Why is writing to an external SD card (UHS-1 class), ext4 formatted,
slow on Jetson TK1 builtin SD slot ?
ubuntu@tegra-ubuntu:~$ dd bs=1M count=2048 if=/dev/zero of=test conv=fdatasync
2048+0 records in
2048+0 records out
2147483648 bytes (2.1 GB) copied, 93.6845 s, 22.9 MB/s
The card is a 64GB Transcend UHS-1 U3 specified with 95 MB/s read and 60 MB/s write speed.
(On an x86 PC with USB 3.0 card reader I already reached this performance)