Very slow write speeds on nvme rockpi4C on kernel 5.10.21



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@Salvador Liébana I would be very cautious about comparing with results that I don't know how they were obtained. In fact I would avoid it ;-)

We cannot say much about Radxa's benchmarking looking at the presented graph.


Nonetheless below you will find the iozone run I performed with LK 5.10.20:

piter@rockpi-4c:~$ uname -a
Linux rockpi-4c 5.10.20-rockchip64 #1 SMP PREEMPT Fri Mar 5 10:47:39 CET 2021 aarch64 GNU/Linux


It was performed using iozone (429) on EXT4 with ROCK Pi 4C and Corsair Force MP510B 480GB (yes, the model with degraded flash chips):


piter@rockpi-4c:~$ iozone -e -I -a -s 1G -r 4k -r 512k -r 16M -i 0 -i 1 -i 2
	Iozone: Performance Test of File I/O
	        Version $Revision: 3.429 $
		Compiled for 64 bit mode.
		Build: linux

	Contributors:William Norcott, Don Capps, Isom Crawford, Kirby Collins
	             Al Slater, Scott Rhine, Mike Wisner, Ken Goss
	             Steve Landherr, Brad Smith, Mark Kelly, Dr. Alain CYR,
	             Randy Dunlap, Mark Montague, Dan Million, Gavin Brebner,
	             Jean-Marc Zucconi, Jeff Blomberg, Benny Halevy, Dave Boone,
	             Erik Habbinga, Kris Strecker, Walter Wong, Joshua Root,
	             Fabrice Bacchella, Zhenghua Xue, Qin Li, Darren Sawyer,
	             Vangel Bojaxhi, Ben England, Vikentsi Lapa.

	Run began: Thu Mar 25 19:37:30 2021

	Include fsync in write timing
	O_DIRECT feature enabled
	Auto Mode
	File size set to 1048576 kB
	Record Size 4 kB
	Record Size 512 kB
	Record Size 16384 kB
	Command line used: iozone -e -I -a -s 1G -r 4k -r 512k -r 16M -i 0 -i 1 -i 2
	Output is in kBytes/sec
	Time Resolution = 0.000001 seconds.
	Processor cache size set to 1024 kBytes.
	Processor cache line size set to 32 bytes.
	File stride size set to 17 * record size.
                                                              random    random     bkwd    record    stride
              kB  reclen    write  rewrite    read    reread    read     write     read   rewrite      read   fwrite frewrite    fread  freread
         1048576       4   100179   166395   178300   179572    52739   110763
         1048576     512  1079229  1073992   903277   903298   902415  1119885
         1048576   16384  1493074  1482710  1572587  1577645  1577413  1482543

iozone test complete.



As you can see it reaches 1GB+/s speeds both writing and reading with large enough block size, hovers around 1GB/s with medium block size and dives to 50-200MB/s with small blocks.


pcie-gen2 overlay is not needed with ROCK Pi 4C as unsupported gen2 link speed was mainlined for all ROCK Pi 4 boards.


BTW. Is the guy Jeff Geerling (

If so then I am actually using the way he was using to compare different SD cards' performance with Raspberry Pi ;-)

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