Choice of BDRV_REQUEST_MAX_SECTORS

[Peter Lieven]

Hi,


I am currently debugging a performance issue in qemu-img convert. I think I 
have found the cause and will send a patch later.

But is there any reason why BDRV_REQUEST_MAX_SECTORS is not at least aligned 
down to 8 (4k sectors)?

Any operation that is not able to determinate an optimal or maximum request 
size from a driver will likely use this value and

might generate unaligned requests (as qemu-img convert does) as soon as the 
first iteration of an operation is done.


Peter