1. Porting DMTCP to Mac OS X
Liang Yu Xiang Gong
College of Computer and Information Science College of Electrical and Computer Engineering
Northeastern University Northeastern University
Boston MA 02215 Boston MA 02215
Email: liangyu@ccs.neu.edu Email: gong.xi@ece.neu.edu

2. What is the DMTCP?
• DMTCP
(Distributed
Mul2Threaded
Checkpoin2ng)
• A
tool
to
transparently
checkpoint
the
state
of
mul2ple
simultaneous
applica2ons,
including
mul2-­‐
threaded
and
distributed
applica2ons.
• hCp://dmtcp.sourceforge.net/

3. Why porting to Mac
• Mac
is
used
extensively
• No
DMTCP
in
Mac
recently

4. How to do that?
What
informa2on
of
a
process
we
should
pay
aCen2on
to:
• libraries
• data
• stack
• heap
• threads
• open
file
descriptors
• signal
status
• mutexes
• process
envrionment

5. How implemented in Linux
and some Unix

6. But when it comes
to Mac OS X ...

7. In Mac
Distinction in Some Commands

8. In Mac
Distinction in System Construction

9. WHAT SHOULD WE DO?

10. Option One :

11. How to Construct a Linux-like
Procfs in Mac OS X:
• Is
MacFUSE
the
perfect
solu2on
for
us?
• MacFUSE
is
a
Mac
OS
X
implementa2on
of
the
FUSE
(File
System
in
User
Space)
mechanism.

12. We feel less hope,
then we try another method.

13. Then, we roll back to the previous
problem, thinking an alternative.

14. Option Two:

15. The VMA of a Process
in Details

16. A Demo
• Find the Memory Range for the stack

17. Different mechanisms when it
comes the memory boundary
• Signal
Func2on
• Sigac2on
Func2on
-­‐-­‐
If
you
use
a
global
variable
to
flag
a
signal
from
a
signal-­‐handler
func2on,
it
should
be
of
the
special
type
sig_atomic_t.
• System
Call
Abuse
-­‐-­‐
e.g.
access()
system
call.

18. Quick Video Demo – Find Heap

19. Probing the Libraries
• Considerably
Complicated
• Right
now,
we
choose
“libc”
as
a
beginning,
and
we
make
it.

20. What discovered during the work
VS

21. Enhanced Access() Usage

22. Result of Enhanced Access()

23. FUTURE WORK …

24. • Using
access()
call
to
replace
sigac2on()
call
successes
in
Linux,
but
crashes
on
Mac,
need
to
figure
out.
• Enhanced
Access()
can
only
get
all
the
valid
addresses
in
a
vague
way,
without
showing
which
does
a
segment
of
memory
address
should
belongs
to.
• We
can
only
find
the
memory
range
of
libc,
con2nued
work
is
needed
to
find
other
libs,
if
existed.
• The
access
right
of
each
memory
segment
is
is
also
unknown.

25. Acknowledgments
• We
would
like
to
thank
Prof.
Gene
Cooperman
for
every
instruc2ons
he
gave
to
us
and
for
the
research
spirit
he
conveyed
to
us.
• We
would
like
to
acknowledge
Kapil
and
Vlad,
for
the
system
knowledge
they
taught
us.
• Finally,
I’d
like
to
thank
Mr.
Rick,
a
classmate
in
my
another
course,
for
introducing
me
such
a
wonderful
tool
to
depict
the
sketch.