Re: Advice sought on how to lock multiple pages in ->prepare_write and ->writepage

[Nathan Scott <nathans@sgi.com>]

On Fri, Jan 28, 2005 at 02:53:41PM -0800, Bryan Henderson wrote:
> >Just putting up my hand to say "yeah, us too" - we could also make
> >use of that functionality, so we can grok existing XFS filesystems
> >that have blocksizes larger than the page size.
> 
> IBM Storage Tank has block size > page size and has the same problem. This 
> is one of several ways that Storage Tank isn't generic enough to use 
> generic_file_write() and generic_file_read(), so it doesn't.  That's not a 
> terrible way to go, by the way.  At some point, making the generic 
> interface complex enough to handle every possible filesystem becomes worse 
> than every filesystem driver having its own code.

Supporting blocksizes larger than the pagesize is a pretty common
thing on other Unices, I don't see any reason why there shouldn't
be support for this in the generic routines.  Especially if there
are tricky aspects to interacting with the page cache and getting
the locking right.

OOC, have you folks measured any performance improvements at all
using larger IOs (doing multi-page bios?) with larger blocksizes?

thanks.

-- 
Nathan