Messages in this thread | | | Date | Sat, 10 Oct 2009 23:10:24 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH 00/31] Swap over NFS -v20 |
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On Sat 2009-10-10 14:23:41, Peter Zijlstra wrote: > On Sat, 2009-10-10 at 14:06 +0200, Pavel Machek wrote: > > Hi! > > > > > > One of them > > > > would be the whole VM/net work to just make swap over nbd/iscsi safe. > > > > > > Getting those two 'fixed' is going to be tons of interesting work > > > because they involve interaction with userspace daemons. > > > > > > NBD has fairly simple userspace, but iSCSI has a rather large userspace > > > footprint and a rather complicated user/kernel interaction which will be > > > mighty interesting to get allocation safe. > > > > > > Ideally the swap-over-$foo bits have no userspace component. > > > > > > That said, Wouter is the NBD userspace maintainer and has expressed > > > interest into looking at making that work, but its sure going to be > > > non-trivial, esp. since exposing PF_MEMALLOC to userspace is a, not over > > > my dead-bodym like thing. > > > > Well, as long as nbd-server is on separate machine (with real swap), > > safe swapping over network should be ok, without PF_MEMALLOC for > > userspace or similar nightmares, right? > > Nope, as soon as the nbd-client looses its connection you're up shit > creek.
Oops, right. Putting reconnect logic into the kernel would make sense.
I misunderstood your proposal. I thought you'd want to put nbd-_server_ into the kernel too. I guess we violently agree that that's unneccessary. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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