Re: unified page and buffer cache?

[Phillip Susi <psusi@cfl.rr.com>]

Would it be possible to somehow keep the current buffer heads, but
associate them with the inode such that readahead() on the directory
would work?

On Fri, 2010-05-07 at 20:46 -0400, tytso@mit.edu wrote:
> Ext2 does use the page cache for directories.  Ext3 and Ext4 access
> directories via buffer heads because of the journaling requirement.
> 
> In *theory* they could be modified to use the page cache, given that
> we can do data journaling for files, and files live in the page cache
> --- however, for cases where the PAGE_SIZE > FS_BLOCKSIZE, which will
> happen if you are using 1k or 2k block filesystems, or on the Power
> Architecture or on the Itanic where the page size is 16k, updates to
> the directory will be much less efficient, since we journal changes to
> data files on page granularity and not buffer granuality.
> 
> Furthermore, someone would have to supply me with the patches; it's
> pretty low on my priority list.  And people on the Power and ia64
> platforms won't be happy....
> 
> 						- Ted