[Colloq] PhD Defense - Kapil Arya - May 5th, 2pm, 366 WVH - Process Virtualization in the Context of Checkpoint-Restart and Virtual Machines

[Jessica Biron]

Kapil Arya 



When: Mon May 5, 2pm 



Where: 366 WVH 



Title: Process Virtualization in the Context of Checkpoint-Restart and Virtual Machines 



Abstract: 



Checkpoint-Restart is the ability to save a set of running processes to 

a checkpoint image on disk, and to later restart it from the disk. In 

addition to its traditional use in fault tolerance, recovering from a 

system failure, it has numerous other uses, such as for application 

debugging and save/restore of the workspace of an interactive 

problem-solving environment. Transparent checkpointing operates without 

modifying the underlying application program, but it implicitly relies 

on a "Closed World Assumption" --- the world (including file system, 

network, etc.) will look the same upon restart as it did at the time of 

checkpoint. This is not valid for more complex programs. Until now, 

checkpoint-restart packages have adopted ad hoc solutions for each case 

where the environment changes upon restart. 



This dissertation presents "process virtualization" to decouple 

application processes from the external environment. A thin 

virtualization layer is introduced between the application and each 

external subsystem. It provides the application with a consistent view 

of the external world and allows for checkpoint-restart to succeed. The 

ever growing number of external subsystems makes it harder to deploy and 

maintain virtualization layers in a monolithic checkpoint-restart 

system. To this extent, an "adaptive plugin" based approach is used to 

implement the virtualization layers that allow the checkpoint-restart 

system to grow organically. 



The principle of decoupling the external subsystem through process 

virtualization is also applied in the context of virtual machines for 

providing a solution to the long standing "double-paging" problem. 

Double-paging occurs when the guest attempts to page out memory that has 

previously been swapped out by the hypervisor and leads to long delays 

for the guest as the contents are read back into machine memory only to 

be written out again. The performance rapidly drops as a result of 

significant lengthening of the time to complete the guest I/O request. 





Committee: 



Gene Cooperman (advisor), College of Computer and Information Science, Northeastern University 



Pete Manolios, College of Computer and Information Science, Northeastern University 



Alan Mislove, College of Computer and Information Science, Northeastern University 



Wil Robertson, College of Computer and Information Science, Northeastern University 



Alex Garthwaite, Twitter, Inc.