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SubjectRe: [RFC][PATCH 8/8] check files for checkpointability
Quoting Dave Hansen (dave@linux.vnet.ibm.com):
>
> Introduce a files_struct counter to indicate whether a particular
> file_struct has ever contained a file which can not be
> checkpointed. This flag is a one-way trip; once it is set, it may
> not be unset.
>
> We assume at allocation that a new files_struct is clean and may
> be checkpointed. However, as soon as it has had its files filled
> from its parent's, we check it for real in __scan_files_for_cr().
> At that point, we mark it if it contained any uncheckpointable
> files.
>
> We also check each 'struct file' when it is installed in a fd
> slot. This way, if anyone open()s or managed to dup() an
> unsuppored file, we can catch it.
>
> Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>

So on a practical note, Ingo's scheme appears to be paying off. In
order for any program's files_struct to be checkpointable right now,
it must be statically compiled, else ld.so (I assume) looks up
/proc/$$/status. So since proc is not checkpointable, the result
is irreversibly non-checkpointable.

So... does it make sense to mark proc as checkpointable? Do we
reasonably assume that the same procfile will be available at
restart?

-serge


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