Re: process checkpointing

Harvey J. Stein (hjstein@bfr.co.il)
16 Dec 1998 17:15:11 +0200


carguin@iname.com writes:

> What's giving me hangups now is anonymous mapping. Currently, when I dump
> a page I check if it's device numbers are zero, it's inode is zero,
> and it's entire contents is zero. If so, then I know it is (or could be)
> an anonymous map. But what about those pages that have already been copied
> and written to? In theory I should be able to map them out of the
> checkpoint file, but that means /proc/?/maps will be different than it was
> before check-pointing, and so something might break. I'm not really sure
> how to remap those memory regions.

I don't know enough about this stuff to help you with such subtle
points.

> The process can definitely be checkpointed from userspace. Loading it back
> up requires some additional efforts though... I think, for the sake of
> time, I will be devising my own binary format. Having my own binary format
> handler should allow me to mmap the libraries and data exactly where I
> want them, and keep me from polluting the kernel proper. Also, it should
> make it easier (I hope) to port back to 2.0.x. Since the assignment
> requires I modify 2.0.27, not 2.1.131, I'll have to do that at some point
> :)

Doesn't the loader (ld.so) deal with this stuff? If so, you might be
able to get away with just using a different loader, or a different
loader + extremely minor kernel mods.

-- 
Harvey J. Stein
BFM Financial Research
hjstein@bfr.co.il

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