Changing default root filesystem to ext4
james.tunnicliffe at linaro.org
Wed Aug 17 10:48:30 UTC 2011
On 17 August 2011 08:55, Tixy <tixy at clara.net> wrote:
> On Wed, 2011-08-17 at 00:13 -0300, Ricardo Salveti wrote:
>> Yeah, if we're doing this change it seems it would make more sense to
>> jump directly to the btrfs, unless we can demonstrate that the
>> performance is not that superior and have any kind of blocker issues.
>> Do we have any kind of benchmark results comparing each filesystem
>> when using them with SD cards around?
> I'm doing some benchmarking, though it's mostly being aimed at producing
> media access patterns to feed into a simulation tool. From these access
> patterns, btrfs looks a lot worse than any ext file system.
> I just looked at the timestamps of my blktrace logs to get some real
> world timings. For untaring kernel source on one of my good performance
> SD cards on a Beagleboard-xM takes:
> m s
> ext4 3:30
> ext3 8:30
> ext2 5:00
> btrfs 13:40
> nilfs 10:40
> logfs 10:00
> this is using default mount options for file system but with noatime.
> These timings also bear out preliminary results from my simulation code.
> Which I'm glad of :-)
This is odd. When I performed tests btrfs and ext4 were both about the
same speed for copying a mixture of large and small files to. I was
testing them using my laptop card reader though. Tixy: Do you get
similar btrfs vs ext4 results using the same card on an x86 host? Is
your host 64 or 32 bit? I can't find any warnings about btrfs being
slow on 32 bit systems during a quick search, but ZFS certainly works
better on 64 bit systems. Perhaps btrfs is more optimal on 64 bit
systems as well.
One thing I noticed during Ubuntu boot on my Panda was that the mount
process would say that it detected btrfs was running on a flash card
and it had enabled flash mode. I don't know what is different in flash
mode and I don't know if when I let Ubuntu auto-mount a flash card for
testing on my Laptop if it enabled it. The only mount option I can
find that sounds right is "ssd", which isn't on when I just tested it
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