The first important and unachieved goal of uuu is orthogonal persistence.
Phil started to build a transactional store, which could be able to
store "memory pages". What needs to be added to this is the ability to
periodically check for changed pages in memory and store them. This
part isn't so hard... what's more complex is to be able to restart the
system from the saved state. This is why we (especially I) experienced
with various checkpointing libraries and engines. We are trying to
make this run in userspace over linux kernel (but this could be some
other kernel too...). But checkpointing/restarting has some problems:
sockets/files as well as threads. The file pointers (and especially
sockets) are not easy to save/restore because they can get closed
remotely (for one reason at least). As for threads, kernel threads
can't hardly be saved by userspace code. So, we would require
userspace threads. It somewhat worked using gnu pthread and ckpt
(probably one of the last "uuu over linux" version in the repository),
but still had a long way to go, especially in order to use the
transactional store.
In other words: we made tests with some tools, but nothing is complete
enough so Phil started to make our own store but then time evaporated
and it hanged there.
On 1/11/06, Dr. Dr. Ruediger M. Flaig <flaig@xxxxxxxxxx> wrote:
> Dear all,
>
> there seems to be some consent that we'd better get going, but that it's
> currently difficult due to lack of defined short-time goals. I guess that's
> how we can phrase it?
>
> So maybe that's a point to start... have our core developers outline Uuu
> precisely, have the community affirm this, then break down the overall
> concept into doable parts and assign them to whoever volunteers. NOW! :-)
>
> Best wishes,
> Ruediger
>
>
>
>
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--
Jacques Mony
Programmeur-Analyste
Les services conseils Systématix inc.
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