Patrick Tullmann, Jay Lepreau, Bryan Ford, and Mike Hibler. User-level checkpointing through exportable kernel state. In Proc. 5th Intl. Workshop on Object Orientation in Operating Systems, Seattle, WA, Oct 1996.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....or even modify internal metadata of the kernel. In our system, this is achieved by converting the metadata into an external representation before exporting it to user level. It has already been shown that this can be done safely, i.e. without enabling applications to increase their privileges [53]. When the external representation is returned to the kernel, the original metadata can be fully reconstructed. We demonstrate the feasibility of our scheme by applying it to an existing kernel, the L4 microkernel. Previous L4 implementations have mostly used fixedsize kernel memory pools with ....

....kernel state to user level Several existing kernels are able to export their internal state to user level. However, this feature has been used mainly to implement process migration and orthogonally persistent operating systems, and not to make kernel memory preemptible. The Fluke microkernel [16, 53] makes every exported operation fully interruptible and restartable. Thus, the complete state of a thread can always be exposed to user level, even when it is involved in a system call. All kernel state is kept in user visible kernel objects, so called flobs, and can be cleanly exported and ....

Patrick Tullmann, Jay Lepreau, Bryan Ford, and Mike Hibler. User-level checkpointing through exportable kernel state. In Proceedings of the Fifth International Workshop on Object Orientation in Operating Systems, Seattle, WA, Oct 1996. IEEE.

....performs a consistency check of critical kernel data structures. This catches possible implementation bugs and prohibits these from stabilize in the system, rendering the system unusable. This check is unnecessary in L4 since no critical kernel structures are included within the checkpoint. Fluke [14] is a kernel that exports user visible, partly pickled kernel objects to the user. This way a user level checkpointer pickles the remaining parts of the kernel objects and save these along with the memory image of the tasks. Grasshopper [16] is a larger system, because it is not based upon ....

Patrick Tullmann, Jay Lepreau, Bryan Ford and Mike Hibler, Userlevel checkpointing through exportable kernel state, Proceedings of the 5th International Workshop on Object-Orientations in Operating System (IWOOOS'96), Seattle, WA, October 1996.

....This catches possible kernel implementation bugs, and prohibits these bugs to stabilize in the system. A checkpoint in L4, on the other hand, does not include any critical kernel data structures. Doing such a consistency check is therefore unnecessary. In contrast with L3 and EROS, Fluke [15] is a kernel o ering transparent checkpointing at user level. This is achieved by having the kernel export uservisible, partly pickled, kernel objects. The checkpointer pickles the remaining parts of the objects and saves them to stable storage together with the memoryimages of the tasks. Most ....

Patrick Tullmann, Jay Lepreau, Bryan Ford, and Mike Hibler. User-level checkpointing through exportable kernel state. In Proceedings of the 5th International Workshop on Object-Orientation in Operating System (IWOOOS '96), Seattle, WA, October 27-28 1996.

....the provision of kernel calls that combine common case IPC operations, such as reversing a connection and then listening for messages, into single calls. This separation of the interface into many explicit micro operations is necessary to support interruptible and restartable kernel operations [22, 24], another important aspect of the Fluke operating system. Whereas the IPC interface is somewhat complex and unwieldy, Fluke s overall IPC system is relatively simple, at least compared to Mach. The absence of features found in Mach based systems, such as port migration, reference counting and ....

P. Tullmann, J. Lepreau, B. Ford, and M. Hibler, "User-level checkpointing through exportable kernel state," in Proceedings of the Fifth International Workshop on Object Orientation in Operating Systems, October 1996.

....to be provided outside of the kernel, a feature appropriate for mobile code platforms [45] Third, the model is a complete process model: it speci es interprocess communication and synchronization primitives in addition to the basic process abstraction. Finally, I have experience with Fluke [21, 22, 46, 47]. Java was chosen as the host language for Alta because it provides the typesafety, language level access control, and run time environment necessary for an extensible system [32] Java is also popular, and is used in a number of widespread systems, such as web servers and web browsers, that ....

....processes P2 and the root cooperate for step (b) Any of these processes can refuse to share the capability, thereby stopping C1 and C2 from communicating directly. 10 Grand Parent on the other two interfaces. To support user level virtual memory servers and exible, user level checkpointers [46], Fluke provides a mechanism for a process to extract the kernel state of any low level object (see Section 3.2.7) It is not necessary that all actual kernel state be exported, but that any state not exported can be derived from state that is exported. For example, in Fluke a parent must be ....

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Tullmann, P. A., Lepreau, J., Ford, B. A., and Hibler, M. J. Userlevel checkpointing through exportable kernel state. In Proceedings of the Fifth International Workshop on Object Orientation in Operating Systems (Seattle, Washington, Oct. 1996), IEEE, pp. 85-88. 104

....is that if a multi stage IPC operation in Fluke is interrupted, the kernel may occasionally modify the user mode instruction pointer to refer to a different system call entrypoint in addition to updating the other user mode registers to indicate the amount of data remaining to be transferred. In [31] we more fully discuss the consequences of providing an atomic API. In summary, the purely atomic API greatly facilitates the job of user level checkpointers, process migrators, and distributed memory systems. The correct, prompt access to all relevant kernel state of any thread in a system makes ....

P. Tullmann, J. Lepreau, B. Ford, and M. Hibler. User-level Checkpointing Through Exportable Kernel State. In Proc. Fifth International Workshop on Object Orientation in Operating Systems, pages 85--88, Seattle, WA, Oct. 1996. IEEE.

.... One of these kernels explored implementations of high performance kernel mediated capabilities and IPC paths, and took about 2 weeks to develop from scratch; the other explored interruptibilityof kernel operations at arbitrary points (finding a more final expression in Fluke s atomic operations [18]) which took only a month. We have found this ability to prototype radical designs in a real kernel to be crucial to choosing designs that are worth fully developing. 2 Toolkit design The Flux OS Toolkit is a framework and set of modularized library code, together with extensive documentation ....

P. Tullmann, J. Lepreau, B. Ford, and M. Hibler. User-level Checkpointing Through Exportable Kernel State. In Proc. Fifth International Workshopon Object Orientation in Operating Systems, pages 85--88, Seattle, WA, Oct. 1996. IEEE.

....Client and server directly manipulate each other s state, and may block waiting for the other. Additionally, as a fully reliable protocol, both sides of the connection must remain consistent. The factor which most complicates the implementation is the interruptibility of Fluke s reliable IPC [19]. Internally, threads can post cancel operations to other threads. When the target thread handles a cancel it must cleanly backtrack, undoing part or all of the system call it is performing; analogous to a processor s handling of precise exceptions. In sum, Fluke IPC is important and highly ....

P. Tullmann, J. Lepreau, B. Ford, and M. Hibler. User-level checkpointing through exportable kernel state. In Proc. Fifth International Workshop on Object Orientation in Operating Systems, pages 85--88, Seattle, WA, Oct. 1996. IEEE.

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Patrick Tullmann, Jay Lepreau, Bryan Ford, and Mike Hibler. User-level checkpointing through exportable kernel state. In Proc. 5th Intl. Workshop on Object Orientation in Operating Systems, Seattle, WA, Oct 1996.

No context found.

Patrick Tullmann, Jay Lepreau, Bryan Ford, and Mike Hibler. User-level checkpointing through exportable kernel state. In Proc. 5th Intl. Workshop on Object Orientation in Operating Systems, Seattle, WA, Oct 1996.

No context found.

Patrick Tullmann, Jay Lepreau, Bryan Ford, and Mike Hibler. User-level checkpointing through exportable kernel state. In Proc. 5th Intl. Workshop on Object Orientation in Operating Systems, Seattle, WA, Oct 1996.

No context found.

Patrick Tullmann, Jay Lepreau, Bryan Ford, and Mike Hibler. User-level checkpointing through exportable kernel state. In Proc. 5th IEEE International Workshop on ObjectOrientation in Operating Systems, pages 85-- 88, October 1996.

No context found.

P. Tullmann, J. Lepreau, B. Ford and M. Hibler. "User-level checkpointing through exportable kernel state." In Proceedings of the Fifth International Workshop on Object-Orientation in Operating Systems, pp. 85---88, Oct. 1996.

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