International Business Machines Corporation

Kavitha Ramalingam

Venkat Venkatsubra

Mallesh K Lepakshaiah

Luke Mathew Browning

Perinkulam I Ganesh

Vinit Jain

Vasu Vallabhaneni

Dwip N Banerjee

Khalid Filali-Adib

John Mark McConaughy

David W Sheffield

Manjunath Basappa Muttur

Laurent Dufour

Balamurugan Ramajeyam

Pramod Achyut Bhandiwad

Prithvi Srihari

Uma Krishnan

Shantala G Krishna

Some embodiments of the inventive subject matter are directed to detecting a request, from an application for a first instance of an operating system (OS) running a first version of the OS, to access a symbol via a special file that accesses kernel memory directly. A second instance of the OS, which manages the first OS, receives the request. The second instance of the OS runs a second version of the OS and includes a kernel shared between the first and second instances of the OS. Some embodiments are further directed to detecting data associated with the symbol, where the data is in a first data format that is compatible with the second version of the OS but incompatible with the first version of the OS and reformatting the data from the first data format to a second data format compatible with the second version of the OS.

Abstracting special file interfaces to concurrently support multiple operating system levels

Some examples include a system, a computer program product, an apparatus, and the like, configured to perform operations to access, in response to a request by a first instance of an operating system, data stored in a memory of a kernel of a second instance of the operating system. The operations are further to determine whether the data stored in the memory of the kernel of the second instance of the operating system is in a data format that is compatible with the first instance of the operating system. The operations are further to provide the data in the data format that is compatible with the first instance of the operating system. For instance, in some examples, the operations are to determine that the data is in a format incompatible with the first instance of the operating system, and reformat the data in the data format compatible with the first instance of the operating system.

When moving workload partitions (WPARs) from machine to machine, operating systems may encounter errors that prevent successful WPAR migration. Recording and reporting errors can be challenging. To move WPARs, the operating system may employ a plurality of software components, such as code residing in user space (e.g., application programs, OS libraries, and shell scripts), code residing in the operating system's kernel, and code residing on remote machines. Embodiments of the invention include a framework that enables all the software components to record errors. The framework can also report the errors to users and processes.

Error handling in a virtualized operating system

Some embodiments of the inventive subject matter are directed to detecting a request to access a symbol via a special file that accesses kernel memory directly. The request can come from an application from a first instance of an operating system (OS) running a first version of the OS. A second instance of the OS, which manages the first OS, receives the request. The second instance of the OS includes a kernel shared between the first and second instances of the OS. The second instance of the OS runs a second version of the OS. Some embodiments are further directed to detecting data associated with the symbol, where the data is in a first data format that is compatible with the second version of the OS but is incompatible with the first version of the OS. Some embodiments are further directed to reformatting the data from the first data format to a second data format compatible with the second version of the OS.

A versioned workload partition (WPAR) can be migrated from a source machine to a destination machine. Each thread associated with a process executing within the versioned WPAR is frozen. For each thread associated with the process, an error number associated with the thread is received in response to freezing execution of the thread and at least a current state of the thread is determined as checkpoint information associated with the thread based, at least in part, on the error number associated with the thread. The checkpoint information associated with the one or more threads is provided to the destination machine. The checkpoint information is used at the destination machine to reconstruct the process within a destination versioned WPAR on the destination machine.

Mobility of versioned workload partitions

A computer implemented method, apparatus, system, and computer usable program code for updating a domain name server. In response to detecting a failed network interface in a plurality of network interfaces on a content server, the content server identifies an IP address for the failed network interface. The content server notifies a domain name server that the IP address for the failed network interface is an unreachable IP address. The domain name server does not provide the unreachable IP address to a querying client.

Method and apparatus for updating a domain name server

A computer implemented method, data processing system, and computer program product for efficiently using disk space when unarchiving files in the same file system. An archive file is read to identify a total number of data files in the archive file. The number of headers in the archive file is determined based on the total number of data files. A location in a first disk space of a largest data file in the archive file is determined from an offset in a header corresponding to the largest data file. The largest data file is then copied from the first disk space to a second disk space. The first disk space occupied by the largest data file is then released by truncating the archive file. The obtaining, copying, and releasing steps are repeated for each data file in the archive file until all of the data files are unarchived.

Method to efficiently use the disk space while unarchiving

A method, system, and program provide for efficient send socket call handling by a transport layer. A transport layer of a network protocol stack receives a send socket call for data of a specified length from an application layer. Responsive to detecting that there is insufficient memory for a single memory allocation to a buffer in the transport layer for at least the specified length, the transport layer blocks the send socket call. The transport layer only wakes the send socket call upon detection of sufficient memory for the single memory allocation within the buffer of the transport layer for at least the specified length, wherein waking the send socket call triggers a kernel to perform the single memory allocation in the buffer and to write the data to the single memory allocation in a single pass.

Efficient send socket call handling by a transport layer

A method, network receiver and TCP network that enables a receiver-side triggering of the fast retransmit mechanism when a TCP packet/segment is lost or received out-of sequencing order. The receiver is enhanced with a Fast Retransmit Support (FRS) utility that monitors when a next received packet is out-of-order and responds by transmitting a duplicate acknowledgment (ACK) response that includes therein the same window value as the previous ACK. By including the previous clock time, even when the current window value has advanced, the fast retransmit algorithm at the transmitter is triggering before the timeout period.

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Bengaluru, India

Kavitha Ramalingam