Thread: Compiling custom kernels for P1.1 (with fiasco-gen)
View Single Post
ewheelerinc is offline ewheelerinc
2010-11-25 , 07:52
Posts: 7 | Thanked: 5 times | Joined on Aug 2010
#314
Originally Posted by lxp View Post
Hi Eric,
It is awesome someone tries that advanced setups.
I think it wouldn't be neccesary to use raid0 for swap partitions. You could simply add a second swap partition and as far as I know the kernel automatically uses both for best performance.
I haven't done this myself so far, so maybe you could also include this in your performance test.
Regards,
lxp
I know it will do some amount of swap balancing, but I don't know if it distributes swap writes across the same swap priority.

Does anyone know how Linux balances swap-outs across multiple swap devices?

For example, if Linux swaps to every-other-swap-device at page granularity, that may be suboptimal with 4k pages. The erase block size of flash is probably somewhere between 16k and 128k. Ideally we want the RAID0 stripe size to be exactly one erase-block size to minimize write amplification and write to the other block-device while the first is being written to (assuming they are asynchronous, which they should if the SD interfaces use DMA).

Does anyone know the erase-block size of the N900's onboard 32GB flash?

-Eric