Category: linux

UBI Fastmap on the Devkit8000

Tonight I tried the (new) UBI Fastmap feature on the Devkit8000.

For this reason I created a UBI image with ptxdist. The UBI fastmap was not activated in the kernel that installed the UBI image in NAND.

After first boot I got the following output:

[ 2.842315] UBI: attaching mtd5 to ubi0
[ 3.146972] UBI: scanning is finished
[ 3.165374] UBI: attached mtd5 (name "File System", size 121 MiB) to ubi0

That make around 300 ms from “attaching…” to “attached …”.

Then I activated UBI fastmap in the kernel configuration and got the following output:

[ 2.839019] UBI: default fastmap pool size: 45
[ 2.843780] UBI: default fastmap WL pool size: 25
[ 2.848754] UBI: attaching mtd5 to ubi0
[ 3.154663] UBI: scanning is finished
[ 3.173156] UBI: attached mtd5 (name "File System", size 121 MiB) to ubi0

After changing the bootargs in the bootloader U-Boot and adding ubi.fm_autoconvert=1 there is nothing to see from conversion:

[ 2.839019] UBI: default fastmap pool size: 45
[ 2.843780] UBI: default fastmap WL pool size: 25
[ 2.848754] UBI: attaching mtd5 to ubi0
[ 3.154663] UBI: scanning is finished
[ 3.173156] UBI: attached mtd5 (name "File System", size 121 MiB) to ubi0

But with the next boot ubi fastmap is active:

[ 2.844116] UBI: default fastmap pool size: 45
[ 2.848876] UBI: default fastmap WL pool size: 25
[ 2.853820] UBI: attaching mtd5 to ubi0
[ 2.927093] UBI: attached by fastmap
[ 2.930877] UBI: fastmap pool size: 45
[ 2.934844] UBI: fastmap WL pool size: 25
[ 2.953826] UBI: attached mtd5 (name "File System", size 121 MiB) to ubi0

That are around 100 ms from “attaching …” to “attached…”. For such a small UBIFS with only 121 MiB is it a gain of 200 ms.

Boot times (part 2)

The candidates are this time: gzip, lzma, lzo, xz and uncompressed.
The boot time is measured with grabserial. The image is read from a sd card.

compression method image size loading time decompression time
gzip 3978136 0.327381 0.744222
lzma 2939704 0.245322 2.41247
lzo 4368056 no boot
xz 2792912 0.220659 1.961494
uncompressed 7967108 0.641257 –

Test network speed

One of my actual projects uses a USB-Ethernet (LAN9512) interface. So I am interested in the real speed for this combination.

On the embedded device I used netcat with the following parameters:
nc -l -p 1234 | dd of=/dev/null

And on the host side I used netcat with:
dd if=/dev/urandom bs=4096 count=100000 | nc host.tld 1234

For the different counts I got the following numbers

count duration speed
1000 1 s 4.1 MB/s
10000 10.8 s 3.8 MB/s
100000 108 s 3.8 MB/s
1000000 1092 s 3.7 MB/s

Okay, the last test copied 4.1 GB and lasted 18 minutes.