Messages in this thread | | | Date | Thu, 14 Aug 2008 07:53:02 +0200 | From | Pavel Machek <> | Subject | Re: [RFC][PATCH 1/4] checkpoint-restart: general infrastructure |
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Hi!
> > > > I have to wonder if this is just a symptom of us trying to do this the > > > > wrong way. We're trying to talk the kernel into writing internal gunk > > > > into a FD. You're right, it is like a splice where one end of the pipe > > > > is in the kernel. > > > > > > > > Any thoughts on a better way to do this? > > > > > > Maybe you can invert the logic and let the new syscalls create a file > > > descriptor, and then have user space read or splice the checkpoint > > > data from it, and restore it by writing to the file descriptor. > > > It's probably easy to do using anon_inode_getfd() and would solve this > > > problem, but at the same time make checkpointing the current thread > > > hard if not impossible. > > > > Yeah, it does seem kinda backwards. But, instead of even having to > > worry about the anon_inode stuff, why don't we just put it in a fs like > > everything else? checkpointfs! > > One reason is that I suspect that stops us from being able to send that > data straight to a pipe to compress and/or send on the network, without > hitting local disk. Though if the checkpointfs was ram-based maybe not? > > As Oren has pointed out before, passing in an fd means we can pass a > socket into the syscall.
If you do pass a socket, will it handle blocking correctly? Getting deadlocked task would be bad. What happens if I try to snapshot into /proc/self/fd/0 ? Or maybe restore from /proc/cmdline?
-- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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