On Fri, 4 Oct 2002, Badari Pulavarty wrote:
>
> Only issue would be the alignment restriction on blockdev versus raw device.
Hmm.. We might want to revert the stuff that made the default block device
alignment be the maximal possible, and instead make the default be the
minimum possible.
The offending code is the "while"-loop in bd_set_size(). Just removing
that should make the default size be the minimal one (ie hardsect_size).
It _used_ to make sense to try to maximize the block-size, since it had a
noticeable impact on performance whether we did 8 512-byte requests or
just 1 4kB request. However, all the bio changes have likely made that a
non-issue, since Andrew's code ends up doing things directly one page at a
time _anyway_.
Of course, mounting a filesystem on the device will override the default
anyway, so this by no means will guarantee that direct access will always
have the minimal alignment restrictions, but once you've mounted a 4kB
blocksize filesystem on that device I think you might as well do 4kB
chunks even if you open it through the device interface, no?
Linus
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