[ENBD] What about swapping via enbd

[Peter T. Breuer]

"A month of sundays ago Hans-Peter Jansen wrote:"
> [not yet subscribed. Please CC: me]

MMM .... may be a bit late. I'll try and bounce it to you later.

> thanks to freshmeat, I got aware of this project. Around a year
> ago, I tried to use nbd as a swap device with not much success..

I believe somebody found out how to do it, and I embedded the trick
into the code as a -s flag (clientside?).

> My standard usage pattern of linux is diskless. Therfore one of
> the long standing items on my personal wishlist is swapping
> reliably via nbd. (The other item is suspend to nbd :).
> 
> Some comments on this are highly appreciated.

Well, the client accepts "-s". There might be a leeetle bug in the
cmdline parser there now that I look (ahem, ahem) but I think it should
work, although it may set the number of channels to 1 ...

Can you try it and let me know? The cmdline option seems to set the
flag NBD_CLIENT_SWAPPING, which it turn causes the client to lock
itself into memory with an mlockall() call. That prevents it swapping
itself out over itself, which would be, uh, difficult to recover from.

Peter