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  • Batch processing of requests in a data processing network
    Publication number: 20040194087
    Abstract: A method and system in which client requests to a multi-server, local area network (server cluster) are accumulated during discrete time intervals (batching periods), but not processed immediately. The servers are initialized to a low power state. At the end of a batching period or upon occurrence of some other specified event, the server cluster selects one or more servers to process the accumulated requests. The selected servers are then powered on and the requests are distributed to the powered servers for processing and response generation. After all requests have been responded to, the server cluster typically powers down the servers such that servers are actively powered only during the periods when batched requests are being processed. During times when a server cluster's request loading is sufficiently light, the response periods will be significantly shorter than the batching periods.
    Type: Application
    Filed: April 11, 2002
    Publication date: September 30, 2004
    Applicant: International Business Machines Corporation
    Inventors: Bishop Chapman Brock, Elmootazbellah Nabil Elnozahy, thomas Walter Keller,, Ramakrishnan Rajamony, Freeman Leigh Rawson
  • Method and system for replication support in a remote method invocation system
    Patent number: 6421701
    Abstract: A method and system are disclosed for enforcing consistency among replicas of a server through the reliable and ordered delivery of client requests via an ordering multicast protocol in association with a deterministic and pre-emptive scheduler in a computer network having at least one client connected to a replicated server. The scheduler enforces an execution order that conforms with the request ordering specified by the multicast protocol. The deterministic scheduler subdivides execution streams into instruction slices such that the number of instructions within each slice is pre-determined. An instruction counter is used to generate an interrupt at the expiration of an instruction slice. A thread is scheduled at the beginning of an instruction slice, such that all scheduling decisions are identical among all server replicas. Therefore, all scheduling decisions are identical everywhere, eliminating the nondeterminism due to time-based scheduling of traditional thread schedulers.
    Type: Grant
    Filed: January 29, 1999
    Date of Patent: July 16, 2002
    Assignee: International Business Machines Corporation
    Inventor: Elmootazbellah Nabil Elnozahy
  • Superpage coalescing which supports read/write access to a new virtual superpage mapping during copying of physical pages
    Patent number: 8417913
    Abstract: A method of assigning virtual memory to physical memory in a data processing system allocates a set of contiguous physical memory pages for a new page mapping, instructs the memory controller to move the virtual memory pages according to the new page mapping, and then allows access to the virtual memory pages using the new page mapping while the memory controller is still copying the virtual memory pages to the set of physical memory pages. The memory controller can use a mapping table which temporarily stores entries of the old and new page addresses, and releases the entries as copying for each entry is completed. The translation lookaside buffer (TLB) entries in the processor cores are updated for the new page addresses prior to completion of copying of the memory pages by the memory controller. The invention can be extended to non-uniform memory array (NUMA) systems.
    Type: Grant
    Filed: November 13, 2003
    Date of Patent: April 9, 2013
    Assignee: International Business Machines Corporation
    Inventors: Elmootazbellah Nabil Elnozahy, James Lyle Peterson, Ramakrishnan Rajamony, Hazim Shafi
  • Method and system for compressing reduced instruction set computer (RISC) executable code
    Patent number: 6442680
    Abstract: A method and system for a compression scheme used with program executables that run in a reduced instruction set computer (RISC) architecture such as the PowerPC is disclosed. Initially, a RISC instruction set is expanded to produce code that facilitates the removal of redundant fields. The program is then rewritten using this new expanded instruction set. Next, a filter is applied to remove redundant fields from the expanded instructions. The expanded instructions are then clustered into groups, such that instructions belonging to the same cluster show similar bit patterns. Within each cluster, the scopes are created such that register usage patterns within each scope are similar. Within each cluster, more scopes are created such that literals within each instruction scope are drawn from the same range of integers. A conventional compression technique such as Huffman encoding is then applied on each instruction scope within each cluster.
    Type: Grant
    Filed: January 29, 1999
    Date of Patent: August 27, 2002
    Assignee: International Business Machines Corporation
    Inventor: Elmootazbellah Elnozahy
  • Memory transaction monitoring system and user interface
    Patent number: 6601149
    Abstract: A system for and method of monitoring memory transactions in a data processing system are disclosed. The method includes defining a set of memory transaction attributes with a monitoring system and detecting, on a data processing system connected to the monitoring system, memory transactions that match the defined set of memory transaction attributes. The number of detected memory transactions occurring during a specified duration are then displayed in a graphical format. In one embodiment, the data processing system comprises a non-uniform memory architecture (NUMA) system comprising a set of nodes. In this embodiment, the detected transactions comprise transactions passing through a switch connecting the nodes of the NUMA system. The set of memory transaction attributes may include memory transaction type information, node information, and transaction direction information.
    Type: Grant
    Filed: December 14, 1999
    Date of Patent: July 29, 2003
    Assignee: International Business Machines Corporation
    Inventors: Bishop Chapman Brock, Eli Chiprout, Elmootazbellah Nabil Elnozahy, Ramakrishnan Rajamony, Freeman Leigh Rawson, III, Ronald Lynn Rockhold
  • Energy-aware workload distribution
    Publication number: 20030079151
    Abstract: The distribution of power dissipation within cluster systems is managed by a combination of inter-node and intra-node policies. The inter-node policy consists of subdividing the nodes within the cluster into three sets, namely the “Operational” set, the “Standby” set and the “Hibernating” set. Nodes in the Operational set continue to function and execute computation in response to user requests. Nodes in the Standby set have their processors in the low-energy standby mode and are ready to resume the computation immediately. Nodes in the Hibernating set are turned off to further conserve energy, and they need a relatively longer time to resume operation than nodes in the Standby set. The inter-node policy further distributes the computation among nodes in the Operational set such that each node in the set consumes the same amount of energy.
    Type: Application
    Filed: October 18, 2001
    Publication date: April 24, 2003
    Applicant: International Business Machines Corporation
    Inventors: Patrick Joseph Bohrer, Bishop Chapman Brock, Elmootazbellah Nabil Elnozahy, Thomas Walter Keller, Michael David Kistler, Ramakrishnan Rajamony
  • Method and system in a computer network for the reliable and consistent ordering of client requests
    Patent number: 6178441
    Abstract: A method and system for reliably and consistently delivering client requests in a computer network having at least one client connectable to one or more servers among a group of servers, wherein each server among the group of servers replicates a particular network service to ensure that the particular network service remains uninterrupted in the event of a server failure. A particular server is designated among the group of servers to manage client requests which seek to update a particular network service state, prior to any receipt of a client request which seeks to update the particular network service state by any remaining servers among the group of servers.
    Type: Grant
    Filed: September 21, 1998
    Date of Patent: January 23, 2001
    Assignee: International Business Machines Corporation
    Inventor: Elmootazbellah Nabil Elnozahy
  • Efficient identification of candidate pages and dynamic response in a NUMA computer
    Patent number: 6499028
    Abstract: A performance monitor configured to count memory transactions and to issue an interrupt to the computer system if the monitor detects a specified number of transactions associated with a particular segment of the physical address space of the system. The monitor includes an interface suitable for coupling to an interconnect network of a computer system and configured to extract physical address information from a transaction traversing the interconnect network, a translation module adapted for associating the extracted physical address with one of a plurality of memory blocks and, in response thereto, incrementing a memory block counter corresponding to the memory block, and an interrupt unit configured to assert an interrupt if the block counter exceeds a predetermined value. The interface unit is configurable to selectively monitor either incoming or outgoing transactions and the translation unit preferably includes a plurality of region filters each comprising one or more of the memory blocks.
    Type: Grant
    Filed: March 31, 1999
    Date of Patent: December 24, 2002
    Assignee: International Business Machines Corporation
    Inventors: Bishop Chapman Brock, Eli Chiprout, Elmootazbellah Nabil Elnozahy, David Brian Glasco, Ramakrishnan Rajamony, Freeman Leigh Rawson, III, Ronald Lynn Rockhold
  • Verification of service level agreement contracts in a client server environment
    Patent number: 6792459
    Abstract: A method, apparatus and computer program product are disclosed to enable independent verification of service level agreement between two parties. In one embodiment, a first party contracts the hosting service of a second party to provide said first party with Web page and services on second party's equipment. Said contract contains a Service Level Agreement specifying performance parameters and guarantees for the response time experienced by users of said Web page and services. Independent verification by a third party of said agreement is done for a fee through several steps. In a first step, said third party inserts measuring and reporting instructions into blocks of information maintained on the server of said second party. The measuring instructions are for delivery to the client with the blocks of information. The delivery of the instructions occurs responsive to a request for the information by the client. Once they are delivered, the instructions are executed by the client.
    Type: Grant
    Filed: December 14, 2000
    Date of Patent: September 14, 2004
    Assignee: International Business Machines Corporation
    Inventors: Elmootazbellah Nabil Elnozahy, Ramakrishnan Rajamony
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