Re: Extended file stat: Splitting file- and fs-specific info?

Dave Chinner [off-list ref] wrote:

quoted

Also, do Dave Chinner's ideas for indicating five I/O parameters want to be
32-bit numbers?  Larger?  Smaller?  Can they be log2?

Definitely 32 bit, IMO, as it's not uncommon to see optimal IO sizes
in the tens of megabytes on large, high bandwidth storage systems.
As for being log2 - that's just making it more complex to use and
making code ugly - we'd have to convert to log2 in kernel, then
convert back in every single application....

ilog2() in the kernel uses the CPU's bit-scan instruction if it has one and
converting back is just a bitshift operator.

But let's go with 32-bit fields for the moment.  I presume we aren't worried
about a driver that wants to do a 4GB transfer...

David