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.