Sunday, February 20, 2011

Hard drive tuning

I just installed Ubuntu Netbook 10.10 on my girlfriend's netbook. I expected it to be slow, but not that slow. It's a ACER ASPIRE ONE 110 netbook, pretty simple, small SSD drive, low memory, though pretty light to carry around.

After googling around a bit, I found some common optimizations for netbooks. Here are the ones I actually did:

1. Remove journaling from ext4

Some previous research indicate that the overhead caused by journaling could be from 4% to 12%. While installing Ubuntu, you can disable the journaling right after the partitions are done (shift to a different tty and use following command). I did it another way around: boot to a live USB drive. The command is

sudo tune2fs /dev/sdN -O ^has_journal

and it removes the journaling feature flag.

2. Mount flags

"noatime" avoids updates on files' access time information for every read you perform on it. I basically prepended "noatime" to the mount flags on /etc/fstab. For more information on other special uses, check this page.

I also tweaked the initialization procedures for moving/removing unimportant stuff for the netbook's use, such as moving bluetooth initialization to user runtime, sudo checks, etc. Another thing that gave a good boost was setting vm.swappiness=20 on /etc/sysctl.conf, which will decrease swapout (throwing programs to the hard drive). This is somehow a dangerous trade-off: RAM is faster but this netbook has only 512MB, it'll be faster as long as you don't keep lots of applications open.

Cheers

Thursday, February 10, 2011

Finally CC2540 gets useful

After some talking with TI engineers, they figured out we were in the wrong pitch. The firmware argued to be BLE compliant indeed exists, though it wasn't the one provided in the software bundle.

One of their engineers was kind enough to provide us a build of the correct one. We can't confirm it's complete, but we managed to perform a successful LE scan and also a LE connection (using BlueZ latest developments on LE).

It seems that now we have an useful platform in our hands. We'll be planning development and syncing with the community in the near future.