SD block driver - ext2 block size

[amio]

Hi All,

Am calculating throughput for my own SD (Secure Digital) card driver. I get very less numbers of throughput for SD cards. I receive only 4KB of data for every request from the file system. I use ext2 filesystem for the card.

I believe the maximum block size of the ext2 filesystem is 4KB. So that the file system gives 4KB per request.

Is there anyway to increase the blocksize of the ext2 filesystem?

i tried "mke2fs –t ext2 –b= 8192" to change the block size but got the error as invalid block size.

Pls help.

Thanks,
amio

[henrikau]

No, read the manpage for mke2fs

-b block-size
Specify the size of blocks in bytes. Valid block-size values are 1024, 2048 and 4096 bytes per block. If omitted, block-size is heuristically determined by the filesystem size and the expected usage of the filesystem (see the -T option). If block-size is negative, then
mke2fs will use heuristics to determine the appropriate block size, with the constraint that the block size will be at least block-size bytes. This is useful for certain hardware devices which require that the blocksize be a multiple of 2k.

Other than hacking on ext2 itself, I don't see any way around this. reiserfs supports 8192B blocks, and other filesystems will have varying sized blocks, to a power-of-two ratio.