Jetson TK1: Maximum write speed on external SD card about 20 MB/s ?

[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)

Late for response but the SD card in Jetson TK1 board is actualy using SDIO interface. We will collect more info on USB 3.0 interface data.


can you provide dmesg logs of jetson-tk1 and desktop, with your SDcard connected, and mention the RAM clock speed during data transfer, your dmesg log would help in checking things.

Also, Pls give the details of the card like, manufacturer code, picture if possible