Re: Bio pool & scsi scatter gather pool usage

[Alan Cox]

> But this gets you lowest common denominator sizes for the whole
> volume, which is basically the buffer head approach, chop all I/O up
> into a chunk size we know will always work. Any sort of nasty  boundary
> condition at one spot in a volume means the whole thing is crippled
> down to that level. It then becomes a black magic art to configure a
> volume which is not restricted to a small request size.

Its still cheaper to merge bio chains than split them. The VM issues with
splitting them are not nice at all since you may need to split a bio to
write out a page and it may be the last page