On Sun, 12 Mar 2000, Peter J. Braam wrote:
> Alexander Viro wrote:
>
> >
> > 6) unions in superblocks (and inodes) are nasty. Use separately-allocated
> > private parts of either and keep pointer to them in ->u.generic_sbp and
> > ->u.generic_ip, resp. It's less critical for superblocks, but for inodes
> > it is pretty serious.
>
> Is it expensive to allocate that data whenever an inode is brought into
> memory?
>
> Some commercial Unices did this and then backed out in view of the cost.
I know. However, we have a pretty good allocator and we are already using the
thing for inodes themselves. Considering the difference in sizes for different
filesystems... I suspect that we are going to win here, simply because the
memory pressure will go down. Compare the sizes of NFS, ext2 and CODA private
structures...
ObCODA: do you have any sort of alignment for cached directories? It would be
ideal if you could guarantee that no entry crosses 4K-boundary in caching
file...
