Okay, so I got some jffs2 results. First the baseline: default kernel
setup, printks enabled, serial console. What I tested was to mount a
freshly created rootfs. I used the 20080116 snapshot, with a size of
47038464 bytes. So all times below are for the "mount" operation.
As expected, this takes a looong time, with the kernel complaining
bitterly about "Empty flash at ... ends at ...": about 49.5s.
Now, we can cheat and turn kernel messages off. This brings the mount
time down to about 39.2s, or 80% of the initial value.
Then I enabled hardware ECC. Note that the code for this is quite
broken, but as long as there are no real errors, this doesn't matter :-)
This brought it down to about 29.9s, or 60% of the first result.
Then I was getting a bit worried about those error messages. Turns
out the the file system is generated with completely wrong parameters,
i.e., the Flash parameters of the GTA01, not the GTA02. Fixing this
yielded an image of 50069504 (+6.4%), and a mount time of about 8.4s,
or roughly 17% of the initial mess.
Tony, your estimate of -80% was pretty accurate :-)
Finally, I gave summaries a try. They increased the image by 3.4%
and reduced mount time to about 1.2s, or 2.4% of the original time.
The correct mkfs command would be something like this:
mkfs.jffs2 --eraseblock=0x20000 --pagesize=0x800 --no-cleanmarkers \
--little-endian --pad -o rootfs.jffs2 -d ./rootfs
To add the summaries, something like this:
sumtool --eraseblock=0x20000 --no-cleanmarkers \
--littleendian --pad -i rootfs.jffs2 -o srootfs.jffs2
Below is my detailed log. Note that also unmounting takes some time,
something in the order of 8 seconds after the first mount. But that
just seem to be some dirty buffers (probably summary updates) that
eventually get flushed in the background.
So, my conclusion this far is that jffs2 can do quite well if we just
let it. I think summaries are enough of a win that we want to us them,
particularly since they're cheap to use and don't break any assumptions
we make.
- Werner
---------------------------------- cut here -----------------------------------
# ls -l openmoko-devel-image-fic-gta02.jffs2
-rw-r--r-- 1 root root 47038464 Jan 16 08:53
openmoko-devel-image-fic-gta02.jffs2
time scp openmoko-devel-image-fic-gta02.jffs2 192.168.0.1:
real 0m52.649s user 0m1.464s sys 0m1.268s
time flash_eraseall -q /dev/mtd5
real 0m 1.26s user 0m 0.00s sys 0m 1.27s
time nandwrite -p -q /dev/mtd5 openmoko-devel-image-fic-gta02.jffs2
real 0m 24.27s user 0m 0.05s sys 0m 24.22s
time mount -t jffs2 /dev/mtdblock5 /mnt
real 0m 49.49s user 0m 0.00s sys 0m 47.01s
time umount /mnt
real 0m 8.59s user 0m 0.00s sys 0m 0.02s
time mount -t jffs2 /dev/mtdblock5 /mnt
real 0m 49.35s user 0m 0.00s sys 0m 46.90s
time umount /mnt
real 0m 0.03s user 0m 0.00s sys 0m 0.02s
BASELINE: mount 49.5s, umount 0-9s
echo 0 >/proc/sys/kernel/printk
time mount -t jffs2 /dev/mtdblock5 /mnt
real 0m 39.19s user 0m 0.00s sys 0m 36.67s
time umount /mnt
real 0m 0.02s user 0m 0.00s sys 0m 0.01s
SILENT: mount 39.2s
time scp openmoko-devel-image-fic-gta02.jffs2 192.168.0.1:
real 0m52.644s user 0m1.504s sys 0m1.008s
time flash_eraseall -q /dev/mtd5
time nandwrite -p -q /dev/mtd5 openmoko-devel-image-fic-gta02.jffs2
real 0m 22.22s user 0m 0.05s sys 0m 22.18s
time mount -t jffs2 /dev/mtdblock5 /mnt
real 0m 40.10s user 0m 0.00s sys 0m 37.70s
time umount /mnt
real 0m 2.19s user 0m 0.01s sys 0m 0.01s
time mount -t jffs2 /dev/mtdblock5 /mnt
real 0m 40.28s user 0m 0.00s sys 0m 37.67s
time umount /mnt
real 0m 0.02s user 0m 0.01s sys 0m 0.01s
echo 0 >/proc/sys/kernel/printk
time mount -t jffs2 /dev/mtdblock5 /mnt
real 0m 29.92s user 0m 0.01s sys 0m 27.56s
time umount /mnt
real 0m 0.05s user 0m 0.00s sys 0m 0.02s
HWECC+SILENT: mount 29.9s
# rm openmoko-devel-image-fic-gta02.jffs2
# mkfs.jffs2 --eraseblock=0x20000 --pagesize=0x800 ...
# echo 7 >/proc/sys/kernel/printk
# ls -l rootfs.jffs2
-rw-r--r-- 1 root root 50069504 Jan 16 21:37 rootfs.jffs2
time scp rootfs.jffs2 192.168.0.1:
real 0m55.898s user 0m1.532s sys 0m1.336s
time flash_eraseall -q /dev/mtd5
time nandwrite -p -q /dev/mtd5 rootfs.jffs2
real 0m 23.64s user 0m 0.09s sys 0m 23.55s
time mount -t jffs2 /dev/mtdblock5 /mnt
real 0m 8.34s user 0m 0.00s sys 0m 8.33s
time umount /mnt
real 0m 8.46s user 0m 0.01s sys 0m 0.01s
time mount -t jffs2 /dev/mtdblock5 /mnt
real 0m 8.34s user 0m 0.00s sys 0m 8.33s
time umount /mnt
real 0m 0.13s user 0m 0.00s sys 0m 0.01s
HWECC+MKFS: mount 8.4s
# rm rootfs.jffs2
# sumtool ...
# ls -l srootfs.jffs2
-rw-r--r-- 1 root root 51773440 Jan 16 21:39 srootfs.jffs2
time scp srootfs.jffs2 192.168.0.1:
real 0m57.818s user 0m1.576s sys 0m1.404s
time flash_eraseall -q /dev/mtd5
time nandwrite -p -q /dev/mtd5 srootfs.jffs2
real 0m 24.45s user 0m 0.04s sys 0m 24.41s
time mount -t jffs2 /dev/mtdblock5 /mnt
real 0m 1.13s user 0m 0.00s sys 0m 1.12s
time umount /mnt
real 0m 6.68s user 0m 0.01 sys 0m 0.01s
time mount -t jffs2 /dev/mtdblock5 /mnt
real 0m 1.14s user 0m 0.00s sys 0m 1.13s
time umount /mnt
real 0m 0.03s user 0m 0.00s sys 0m 0.02s
HWECC+MKFS+SUM: mount 1.2s
