Experiencing extremely slow SD card write speeds with Nano

The issue:

OS: Jetpack 4.4.1

I am running a Nano/D435i depth camera configuration using Donkey Car v 4.1 and also running a Xavier NX/D435i depth camera using the same DC v 4.1.

I realize that the Xavier NX is faster than the Nano, however we have found the following, running the same Donkey Car v 4.1 software on both processors, based on analysis of the data writer part (TubWriter) performance during data recording:

"Ok - I see the problem. On the Xavier run everything looks ok’ish. If you just look at the ‘avg’ column, this gives you the average runtime in ms per part. So the total of that column (assume everything would run sequentially once per loop) should be less than 1000 / car frequency.

On the Nano the TubWriter part takes more, 1000ms for a single call to run, that’s why the car doesn’t react at all.
Even on the Xavier with avg of 12ms it is not as fast as expected (I think it should be < 5ms).
So something is wrong with your write operations on the Nano. Are you writing to an SD card or a disk, there should be tools to check the i/o performance?"

The car drive loop frequency is 20 Hz.

I am using a SanDisk UHS-I 128GB SD card that has a burst write speed approaching 90Mbs/sec and a sustained write speed of around 30MBs/sec on both the Nano and the Xavier NX.


Please apply the patch here for jp4.4.1 first.


Does Jetpack 4.5.1 include this patch?

Today I ran a Nano 4GB running JP 4.5.1 and DC 4.1 with the D435i depth camera.
Running JP 4.5.1 resulted in the steering and throttle performing normally without latency or hesitation. The TubWriter average time was less than 30ms (Drive loop = 30Hz and Frame Rate = 60Hz) using a SandDisk 64GB Ultra micro SD card which is a far cry from the 1.5 seconds when running JP 4.4.1.
This empirical testing indicates that some versions of JP (4.4.1 or less) prior to JP 4.5.1 would fall back to a SD card write speed of HS and not UHS at boot up and after a reboot.
Therefore a SD card with a minimum write speed of 10Mbs/sec will more than meet the DC TubWriter speed requirements.
What took NVIDIA so long to correct this bug?

Does Jetpack 4.5.1 include this patch?

Yes, rel-32.5 includes this patch.

Is rel-32.5 work fine?


Yes, it is working fine on my Nano as you can see in my post above.

I will try it on my Xavier NX next.