Ns2 project in Malaysia

        Ns2 project in Malaysia The CORRECTclause potentially further reduces monitoring perturbation by relaxing the timing constraints imposed ns2 project in Malaysia on the calculation of the active predicate. This clause allows users to express allowable tolerances in monitoring due to network delays and unsynchronized processor clocks. In this case, if the ns2 project in Malaysia queue size of each queue manager exceeded  within a window of, then the predicate is considered satisfied.

         If the CORRECTclause is omitted, then ns2 project in Malaysia the view is active only when both queue sizes are simultaneously4greater than The NOTIFYclause instructs the monitor to directly communicate in some manner ns2 project in Malaysia the new value  view’s attribute to the application or AC process at port address  on machine. eduwhenever the view becomes active. The maximum latency ns2 project in Malaysia of this notification can also be specified; here the process ns2 project in Malaysia expects to be notified within one second. Again, a long latency provides the monitor flexibility in reducing its overhead. Monitoring message traffic may be reduced by buffering values in user processes, resident monitors, or the central monitor.

    For example, the large value ns2 project in Malaysia specified here allows the central monitor to buffer ns2 projects in Malaysia multiple messages before performing a single message send to the AC with the buffered messages. One implementation used in our system simply “flushes” all buffers ns2 projects in Malaysia of any relevant resident monitors after some maximum permissible delay in reporting has occurred. If the NOTIFYclause is omitted, the monitor is instructed ns2 project in Malaysia to simply update the entry corresponding to the view’s attribute in the database when the view becomes active.

Ns2 project in Singapore

         Ns2 project in Singapore asindicated in, all attribute specifications are compiled into probes and into attributes of entities stored in the database. This is also the case for the attributes ofrelationships that can be monitored. Probe implementations ns2 project in Singapore are linked and loaded with the target application’s processes and resident monitors, and they are registered with the central monitor. Similar actions are taken for the sensor ns2 project in Singapore implementations and the analysis code derived from the view specifications explained next. Attributes that can be monitored constitute the basis from ns2 project in Singapore which the set of actual events to be monitored is drawn.

        That set is specified with the viewlanguageby programmers as a collection of monitoringviewsstated as entities, relationships, and sets ns2 project in Singapore in the database. The sample view below concerns the queue sizes of two QueueManagerobjects. The viewlanguagesyntax accepted by the ns2 project in Singapore prototype described later is similar to that ns2 project in Singapore appearing below. This view is defined to be activewhen the value of queue– Sizeis greater than 24 in both instantiations of QueueManager; this boolean expression on attributes is ns2 project in Singapore termed theACTIVEpredicate.

       When a view is active, the value of itsderived attributes, mentioned in the targetlistof the viewin this case, the target list consists of the single attributethisqueuesizecomputed by the expression QueueManager. are computed and made ns2 project in Singapore available by the monitor to other environment tools, such as the adaptation controller and the graphical display. Since the monitoring system need not collect, record, and ns2 project in Singapore display information at times at which the view is not active , the ACTIVE predicate reduces the amount of work themonitor must do, thereby reducing monitoring perturbation.

Ns2 project in jordan

       Ns2 project in Jordan regarding monitoring, the values of some attributes  may be supplied automatically by the parallel programming system. Other attributes must be defined by the programmer. For example, in the sample ns2 project in Jordan quicksort program, the user may wish to be notified when the size of the Queueobject exceeds some predefined threshold. In that case, the programmer’s monitoring specification ns2 project in Jordan would explicitly define the attribute queuesizeof the Queueobject. The queuesizeattribute may be mapped to a variable called “q-size” in the application’s code. However, ns2 project in jordan attributes may also be defined in terms of multiple variables used in the application program.

      In general, ns2 project in Jordan an attribute’s value is an expression over one or more variables. Attributes are typechecked by the PCS, through which the application was originally coded. again consider the Queueobject of the sample quicksort ns2 project in Jordan program. In order to evaluateworkload balancing among multiple processes performing thens2 project in Jordan sort of unsorted queue subranges, the user may wish to monitorthe attribute requestDurationfor ns2 project in Jordan each element of that queue.

     This attribute is not predefined and is not maintainedas a variable in the code and therefore, cannot be generated bythe PCS.Instead, such ns2 project in Jordan an attribute must be computed for each request from the source code variables beginRequestTime and endRequestTimewhich are maintained in the code in this case. Two ns2 project in jordan simple languages are used for the specification of program monitoring in the context of the E-R model: the attribute language and the view language. All nondefault, monitorable attributes of a parallel program must be explicitly defined with the attributelanguage.

Ns2 project in london

      Ns2 project in London specifically, in the Issos system, the program construction system generates an E-Rprogram description and records it in a main memory databaseaccessible to all system tools, based on the program’s languagens2 project in London specification and on its knowledge of the program’s run-time representation. Other system components The objective of this paper is not to describe and defend theE-R model, ns2 project in london the database supporting it, and their usefulness for tool integration.

      Elsewhere we provide details on the Issos system and describe a more efficient, persistent ns2 project in London anddistributed database implementation Other approaches to tool integration ns2 project in london also exist Here we simply describe a sample program represented with the E-R model, so that the reader may understand the monitor’s view of a parallel program. Consider a ns2 project in london parallel sort program like the various versions of parallel quicksort described in the literature .

             In the object-based Issos programming system, this program is represented ns2 project in London at run-time as objects interacting via invocation messages, much like the representation of distributed programs in Eden The sort program consists of several objects, including a Queue object which contains a process that maintains a queue of unsorted subranges of the ns2 project in london array being sorted and a Sort object which contains multiple internal processes performing the actual sorting of the array. While the Issos run-time system represents the ns2 project in London  program as a set of objects, the monitor views the program with the E-R model, thereby using ns2 project in London a description that is independent of the execution environment’s program representation. With the E-R model, this program.

Ns2 project in United States

       Ns2 project in United States however, note that\ post-execution analysis in our system is restricted to those queries that are possible to ns2 project in United States answer with the partially analyzed information contained in the database. Turn a particular sensor on or off. This operation is performed to trigger a sampled sensor, or to begin or end the trace of a specific program ns2 project in United States attribute, such as the values of one of its variables. The issuer of this command may request to be notified when a condition or set of conditions regarding the variable’s values becomes true. Probe the current value of a program attribute Retrieve the value of a program attribute which the monitor is or has been tracing.

         The value is ns2 project in United States retrievedfrom the monitor’s database. The next section presents a model of information for use by the monitoring system and shows that this model is an appropriate basis for monitoring specifications. Such specifications are compiled into efficient collection and analysis mechanisms that employ the operations just presented.

          In order to make the monitoring system independent of specific languages, compilers, operating systems, etc., we ns2 project in United States describe in terms of an abstract information model based on the information model  the programs for which monitoring is to be performed, the hardware and software environment in which the programs execute, the data to be collected, and ns2 project in United States the calculations to be performed.Our model includes typed entities, typed relationships between entities, and typed sets of both. The model can incorporate static information about parallel programs and about their execution environments , ns2 project in United States thus capturing compile- and load-time program information, hardware configuration, and others.

Ns2 project in Alberta

       Ns2 project in Alberta probes directly access the address spaces of individual processes on that node, thereby providing a convenient mechanism for amp ling.The main advantage of probes over sampled sensors is that the application code ns2 project in Alberta need not be changed for probing, so that the information to be probed may be defined dynamically. Furthermore, when monitoring parallel programs ns2 project in Alberta executing on shared memory machines, the use of probes versus sensors can reduce program perturbation due to monitoring Any monitoring system must address ns2 project in Alberta the storage of the program information it produces.

        Since the primary use of our monitor is dynamic monitoring, we first store all monitoring information in data structures mapped to main memory using the operating system’s virtual memory mechanisms, thereby reducing ns2 project in Alberta the latency of access to such information. For performance reasons, this ns2 project in Alberta collected data, termed the database, does not contain raw data. It contains analyzed data derived from the information collected using sensors and probes. All information stored in the database is tagged with time stamps and locations of occurrence, for use ns2 project in Alberta by dynamic and post-execution analysis of monitoring information.

     The data structures being used are straightforward template structures derived from the information model used for description of monitoring information. Although the virtual memory database can grow to significant size, for long-term persistent information storage, we currently use ad hoc ns2 project in Alberta file structures, but would prefer using a large-scale historical database in order to be able to perform efficient, additional post-execution analyses. Sample post-execution analysis of such stored information may concern additional analysis of interest to the ns2 project in Alberta programmer or the adaptation algorithms, or it may concern the reproduction or replay of program execution .

Ns2 project in Greece

      Ns2 project in Greece the status of the sensor  is kept in the address space  of the sensor’s process and is checked when the sensor is encountered during execution of the application code The resident monitor receives trace data via ns2 project in Greece event recordsgenerated by sensors. Event records contain  a commandidentifier flagging the information as sensor data,  a sensornumber, identifying the reporting sensor, 3 the time atwhich this event was recorded, and  a sensor-specific value.Event ns2 project in Greece records are communicated to the resident monitor bynotification or by message.

     Communication by notificationimplies that the receipt of the record by the resident monitor is  synchronous with the execution of the sensor. Communication by ns2 project in Greece messageimplies that the composition and the receipt of the event record are asynchronous, since the message may be queued for an unknown period of time. When ns2 project in Greece collecting history information regarding the values of the variable Request-Queue-Size, ns2 project in Greece event records can be received asynchronously  if the resident ns2 project in Greece monitor need not immediately know about the occurrence of each change in the variable’s value.

      However, if the resident monitor has to ns2 project in Greece react immediately to the event that Request-Queue-Sizehas exceeded some threshold value, then it must be interrupted synchronously with the event A sampled sensorsimply returns a ns2 project in Greece single event record in response to a sampling request from a resident monitor, again by message or by notification A sampledsensorsimply returns a single event record in ns2 project in Greece response to a sampling request from a resident monitor, again by message or by notification.

Ns2 project in Austria 

        Ns2 project in Austria on the other hand, samplingis the collection of information at the request of the monitor. Sampling may be asynchronous with the ns2 project in Austria occurrence of an event; it is useful when an immediate reaction to an event is not necessary.Sensors are small pieces of code residing within the program being monitored. A sensor may perform either sampling or tracing, and reports information, such as current ns2 project in Austria value and time, to the resident monitor. When to report such information is determined in part by the user at the time of monitoring specification.

      If a sensor ns2 project in Austria also contains analysis code, it is termed an extended sensor. Sensors are generated automatically by the monitor based on the programmer’s specifications of the events to be monitored. However, ns2 project in Austria the insertion of the generated sensors into the application code must be performed manually; automatic placement requires the use of dependency ns2 project in Austria analyses like those used in parallelizing compilers. A sample sensor implementation in Unix  at the top of the next page. This sensor traces the value of a program ns2 project in Austria variable bad-header-chksumsin a network device driver. It assumes the use of Unix sockets for the transmission ofinformation from the sensor to the monitor.

      Our multiprocessor implementation of such a sensor uses shared memory to implement the required message ns2 project in Austria sending primitive.A traced sensorbegins tracing when it is  by the resident monitor; it stops tracing when it is disabled., a sensor tracing the value of the variable Request- Queue-Sizein some particular process of a distributed application using the monitor ns2 project in Austria generates anoutput each time the value of that variable is changed.

Ns2 project in UK

Ns2 project in UK provides the initial description of each program to be monitored, in terms of the information model used within  the environment, rather than in terms of the object-based program model. It also permits the specification of the adaptations ns2 project in UK to be performed for each program compilation and run The AC performs and supervises the specified program adaptations. It requests and receives ns2 project in UK information from the monitor in order to perform adaptations and it receives instructions from the user concerning the adaptations to be performed.

          The Loader and OS are responsible for ns2 project in UK distributed loading, linking, startup, and execution of the object-based parallel program. Theyare also responsible for making available to the monitor and AC certain information regarding the distributed program, such as the mapping of objects to processes and the ns2 project in UK mapping of names used in object invocations to socket identifiers used by the processes implementing an object’s operations The Monitor is responsible for collecting, analyzing, ns2 project in UK and making available the program information required by the  in the next section.

        Also note that collected and analyzed monitoring information as well as initializationtime program ns2 project in UK information available from the loader and operating system may be shared with the adaptation controller either directly or via the database.Information can be collected either by sampling or by tracing. Tracing consists of the reporting of all ns2 project in UK occurrences of an event within a certain interval of time. Tracing is synchronous with the occurrence of an event; it is performed when all occurrences of an event ns2 project in UK must be known   or when each occurrence of an event must be followed by a certain action .

ns2 project in europe Ns2 project in Europe one use of  monitoring information, dynamic adaptation, is illustrated with the sample distributed quicksort program. We conclude with ns2 project in Europe a summary, a comparison with related research, and a discussion of future work. The monitor is responsible for the collection and ns2 project in Europe analysis of distributed program information. Its overall structure is shown in  for one hardware configuration, a distributed research network connected by an EtherNet network. The resident monitor,residing on each network node, collects and analyzes ns2 project in Europe monitoring information about processes executing on that node. The resident monitors report to a central monitorexecuting on the network node on which the monitoring databaseis stored. The central ns2 project in Europe monitor collects and analyzesdistributed information, interacts with the other tools in Issos, and provides a user interface.’ The monitor was operated ns2 project in europe stand-alone and it was used within the Issos system for parallel programming and program adaptation. The different components of the Issos system are depicted The solid, labeled lines between the modules indicate the information ns2 project in Europe exchanged prior to program execution. The dotted lines indicate some of the information ns2 project in Europe exchanges during program execution This figure depicts the generation of an instrumented, compiled, and loaded application; the run-time instrumentation of an application during execution is depicted The function of each component as it relates to the ns2 project in europe monitoring system is described below The PCS is used for program entry, editing, compilation, and initiation of linking and loading. It describes a ns2 project in Europe parallel program as a set of objects interacting via invocation.