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    SubjectRe: [RFC][PATCH 1/4] checkpoint-restart: general infrastructure
    Quoting Dave Hansen (
    > On Sat, 2008-08-09 at 00:13 +0200, Arnd Bergmann wrote:
    > > > 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.

    Using the anon_inodes would also prevent that, but if it makes for a
    cleaner overall solution then I'm not against considering either one
    of course.

    > I'm also really not convinced that putting the entire checkpoint in one
    > glob is really the solution, either. I mean, is system call overhead
    > really a problem here?
    > -- Dave
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