International Business Machines Corporation

Philippe Bergheaud

Marc Philippe Vertes

Dinesh Kumar Subhraveti

Khalid Filali-Adib

Frederic Barrat

Luke Mathew Browning

Reinhard Theodor Buendgen

Martin Schwidefsky

John Mark McConaughy

David W Sheffield

Stephen Bailey Peckham

Sungjin Yook

Christophe Lombard

Laurent Dufour

Donald Ray Stence

Guy Menanteau

Randal Craig Swanberg

Perinkulam I Ganesh

Mechanisms are provided for performing a live update of an operating system. The mechanisms receive an update to an operating system and clone a root volume group associated with an operating system instance executing in a first logical partition of the data processing system to generate a cloned root volume group. The mechanisms apply the update to the cloned root volume group to generate an updated and cloned root volume group and boot a second logical partition of the data processing system using the updated and cloned root volume group. Moreover, the mechanisms migrate application instances and application data to the second logical partition.

Live operating system update mechanisms

A method, system and computer-usable medium are disclosed for managing virtual processor operations. A dynamic loader receives a request to initiate the creation of a new process, followed by a virtual processor being assigned to an isolated execution environment. The dynamic loader then initiates the creation of the new process by mapping kernel data associated with the virtual processor into the address space of the process. The dynamic loader completes the creation of the new process, and its execution is initiated within the isolated execution environment.

Initiating software applications requiring different processor architectures in respective isolated execution environment of an operating system

A method, computer program and system for controlling accesses to memory by threads created by a process executing on a multiprocessor computer. A page table structure is allocated for each new thread and copied from the existing threads. The page access is controlled by a present bit and a writable bit. Upon a page fault the access is provided to one thread. The kernel handles the new page entry creation process and set the page present bits to zero which creates page faults. In a second embodiment, two page table structures are created, one for one thread having access to the address space and the other page table structure shared by all the other threads not having access to the address space.

Method and system to manage memory accesses from multithread programs on multiprocessor systems

A mechanism for replicating programs executing on a computer system having a first storage means is provided. The mechanism identifies the events corresponding to requests from one executing program, which may be different from the executing program to be replicated, which are non-deterministic and identifies the 'Non Abortable Events' (NAE's), which change irremediably the state of the external world that need to be reproduced in the replay of the programs. These events are immediately transferred for replay and the executing program is blocked until the transfer is acknowledged. For the other non-deterministic events, they are logged and sent to the executing program, the executing programs remaining blocked only if the log is full and/or if a timer between two NAEs expires, in this case a log transfer to the standby machine is performed to prepare replication before unblocking of the executing program.

Transfer of event logs for replication of executing programs

Managing access to resources shared among multiple processes within a computer system. Multiple program instances of an application are almost simultaneously executed on multiple processors for fault tolerance. The replication solution supports the recording and subsequent replay of reservation events granting the shared resources exclusive access rights to the processes, when one program code instruction may request access to a set of shared resources in a non-deterministic order.

Deterministic serialization of access to shared resources in a multi-processor system for code instructions accessing resources in a non-deterministic order

Deterministic serialization of access to shared resource in a multi-processor system for code instructions accessing resources in a non-deterministic order

Mechanisms for managing task events during the scheduling period of a task executing on a processor. Only events of specific portions of the scheduling period are logged, wherein a first shared resource access has been granted for the task, this portion of the scheduling period involving gathering all the non-deterministic events which cannot be replayed by simple task re-execution. Other independent non-deterministic event records are still logged as usual when they occur out of the portion of the scheduling period for which a record has been created. This limits the number of logged events during a recording session of an application and limits the frequency of events to transmit from the production machine to the replay machine.

Optimizing deterministic event record and replay operations

A method and system for providing a virtual clock on a computer by multiplying the number of instructions executed by the average instruction execution time. It is however not reliable to use this generic computation for virtualization of application in a fault tolerant system because the virtual clock computed like this quickly deviates from the system clock. A virtual clock computation is provided which includes periodic readjustment of the virtual to the system clock. Also, the errors coming from rounding of the number of executing instruction are suppressed. Taking the assumption that the user instruction counters are maintained synchronized in the operational and the replication computers, replacing the system clock access by a virtual clock when virtualizing applications thus turning the system clock acquisition into a deterministic event. Replicating the system clock access can be thus done by re-executing the application code in the replication machine avoiding transfer of information at each system clock access of the virtualized application programs.

Method and system for providing a deterministic virtual clock

Provided are a method, system, and article of manufacture for providing a process exclusive access to a page including a memory address to which a lock is granted to the process. A request is received for a memory address in a memory device from a requesting process. A lock is granted to the requested memory address to the requesting process. The requesting process is provided exclusive access to a page including the requested memory address for a page access time period. The exclusive access to the page provided to the requesting process is released in response to an expiration of the page access time period.

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Colmar, France

Philippe Bergheaud