Re: Some interesting input from a flash manufacturer

[Ted Ts'o <tytso@mit.edu>]

On Tue, Mar 06, 2012 at 01:44:28PM -0500, Martin K. Petersen wrote:
> >>>>> "Ted" == Ted Ts'o <tytso@mit.edu> writes:
> 
> Ted> As far as the /sys/block/XXX/queue/* framework, certainly.  It's
> Ted> not clear, however, whether or not we should use entirely new
> Ted> parameters, or try to reuse the existing parameters.  For example,
> Ted> would it be better to use optimal_io_size for the flash page size,
> Ted> or the erase block size?
> 
> If we were to use the existing fields we'd probably set min_io to the
> flash page size and optimal_io to the erase block size.

But min_io currently means the smallest size that we're allowed to
write, correct?  And the flash page size could be 128k and 512 byte
writes might be perfectly OK; it's just that writes are more optimal
at 128k, and would be even more optimal at the erbase block size of 4
megs.  That's why I'm not sure it makes sense to use the existing
fields, since it will confuse file system utilities that are reading
those fields.

   	     	       	       	      - Ted