[elysium-developers] Disk block server and block sizes

[Kasper V. L. <ve...@da...>]

I've been looking at the XN code, and it seems that it uses a disk block
size that's equal to the hardware page size (e.g. 4kb). The only problem
with this approach is that it gives us quite a lot of internal
fragmentation, but harddisks are quite cheap anyhow...

The role of the disk block server is then to[1]:

* load harddisk blocks into the buffer cache
* allow mapping cached blocks into application address spaces
* commit cached blocks to the harddisk

The applications will implement their own filesystem(s) on top of this.
We still need to figure out what to do when the buffer cache gets filled
up. 

/Kasper

[1] Please note that this is just the role of the initial - unprotected
- disk block server. Later we'll put restrictions on which cached blocks
can be mapped into application address spaces, but for now it should do
the trick.

-- 
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Kasper Verdich Lund, Computer Science Department, Aarhus University
Office: 34P.218              | Phone: (+45) 8942 5680
Email:  ve...@da...  | WWW: http://www.daimi.au.dk/~verdich