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Re: [Condor-users] condor_compile on OS X

On Tue, Jun 06, 2006 at 04:54:03PM -0400, Adam Bazinet wrote:
> Dear Condor Team,
> I've read a post from April 2005 saying that to implement checkpointing on 
> OS X would be quite a significant effort.  We are wondering if this effort 
> has been attempted, or if there are any plans to implement checkpointing 
> soon. 

No one has spent much time looking into it, and no one is currently working
on it or planning to work on it.

> Are there any significant technical challenges specifically with OS 
> X?  We are meeting with Apple soon and could bring this to their attention 
> if that would be helpful.  Please let us know,

With the transition to Intel, our current thinking on checkpointing is
using a virtual-machine approach. Process-level checkpointing, like Condor
has on Linux, Solaris, etc is probably doable, but a smarter VM scheduler
would be more useful for most cases. 

Mach has some pretty cool APIs for accessing memory in another process
that should make checkpointing much easier. The Apple C library is a
bit more confusing than other platforms, so that could be a challange.

What we'd most like out of Apple is support for the PT_SYSCALL option to
ptrace(), which nearly every other UNIX supports. This call allows you
to stop a process when it makes a system call, and optionally modify the 
call it was about to make.