Ns2 project in Northwest Territories

      Ns2 project in Northwest Territories the result of this action is a balance of request generation and processing. Once this balance is achieved, continued monitoring by tracing queue size using the extended sensor discussed above ns2 project in Northwest Territories would be inefficient. Asa result, the ACturns this sensor off when it has not been notified of a “threshold exceeded” event for more than 1 min. However, since ns2 project in Northwest Territories external conditions, such as changes in Pyramid or Sun loads due to the activities of other users, may change over time, the ACperiodically polls the monitor for the ns2 project in Northwest Territories queue’s size.

       This polling is achieved by means of a probe. The additional costs of monitoring in this example derive from two messages due to the AC’sdynamic ns2 project in Northwest Territories change of the queue threshold to be used for its notification: one local message from AC to central monitor and one message from central to resident monitor, and three messages due to its dynamic deactivation of the sensor  one from the ACto central ns2 project in Northwest Territories monitor, one from central to resident monitor, and one from the resident monitor to the user program.

      The cost of probing after the desired balance has been achieved is small. Each probe consists of one local message from ACto central monitor, one probe request ns2 project in Northwest Territories across the network from central to resident monitor, one message from user process to resident monitor reporting the probe value, one return message from ns2 project in Northwest Territories resident monitor to central monitor, and one local return message from central monitor to AC. To summarize, this example suggests that probes are an ns2 project in Northwest Territories important element of any dynamic monitoring system that must be able to operate with variable overheads at different times during a program’s execution.

Ns2 project in Belgium

       Ns2 project in Belgium the analysis of monitoring information must be distributed and parallelized across the central and resident ns2 project in Belgium monitors and the user processes being monitored. The analysis of monitoring information by resident monitors is essential in order to reduce the message traffic within the monitoring system and to reduce the workload imposed on the central monitor. Some ns2 project in Belgium analysis may also be shifted to the extended sensor itself. For example, a significant improvement in monitoring performance for this example is gained when the ns2 project in Belgium event “threshold exceeded” is computed within the extended sensor itself, so that only a single event record must be transferred from the user program to the resident monitor.  

       To demonstrate the ns2 project in Belgium system’s dynamic variability regarding collection and analysis, and to indicate some tradeoffs between tracing and sampling, we continue monitoring after the ns2 project in Belgium addition of a second ship manager, and observe the performance effects of this adaptation. When doing this, the size of the request queue remains stable for some time after the second ship manager is added.

     However, due to the lack of actual parallelism in the execution ns2 project in Belgium of multiple ship managers on the Pyramid, a balance of request generation and processing is not achieved. To be notified of this imbalance, the ACdynamically ns2 project in Belgium changes the analysis performed by the resident monitor. In this case, it sets a new value for the queue threshold used by the resident monitor immediately after addition of the ns2 project in Belgium second ship manager. Upon being notified of the event “threshold of  exceeded,” the ACthen slows down request generation by the user process by increasing the amount of time it waits between issuing two consecutive commands from its script.

Ns2 project in Czech Republic

       Ns2 project in Czech Republic the monitor’s collection and analysis mechanisms are exercised as follows. For data collection, a traced, ns2 project in Czech Republic extended sensor is embedded into the queue manager’s code. This sensor computes the queue’s current size from the number of executions of queue element additions and deletions, and it notifies the resident monitor of each change in queue size. The ns2 project in Czech Republic resident monitor checks the current size of the queue against its threshold ns2 project in Czech Republic specified by the adaptation controller, in this case  It notifies the central monitor only when the event “threshold exceeded” occurs, as.

        The sensor is tumed on and off by the central and resident monitors in response to commands received from the AC. The ns2 project in Czech Republic distribution of analysis and collection is straightforward. The analysis required for notification of the central monitor and of the AC regarding the event “threshold exceeded” is ns2 project in Czech Republic performed within the user’s code and the resident monitor. As a result, the number of event records to be transferred from the resident to the central monitor is reducedby a factor of roughly fifty, thereby significantly reducing ns2 project in Czech Republic the network message traffic generated by monitoring.

      Specifically, two local messages and one network message are required to tum on the extended senso ns2 project in Czech Republic from AC to central monitor, from central monitor to resident monitor, and from resident monitor to user process. During game execution, the extended sensor generates ns2 project in Czech Republic approximately fifty event records, each recording the addition or deletion of a queue element; these records are sent to the resident monitor as local messages. One message is sent by the resident monitor to notify the central monitor of the event “threshold exceeded.”

Ns2 project in Croatia

      Ns2 project in Croatia the description of the two-dimensional sea is partitioned into sections, with a section manager process responsible for each section. Ship manager processes are responsible for handling requests ns2 project in Croatia dealing with ships, such as moving and firing. All requests are placed into a single, logically centralized queue, maintained by a queue manager process. Ship managers take and ns2 project in Croatia process requests from this queue. The game is driven from a script, with multiple user processes reading this script and issuing requests to the queue manager.

       This distributed ns2 project in Croatia application illustrates several aspects of the monitoring system, including: the operation of the monitor’s distributed components; the interaction between the monitoring ns2 project in Croatia system and other Issos tools; the tradeoffs regarding the use of the monitor’s various collection mechanisms and the tradeoffs regarding the distribution of information analysis; and ns2 project in Croatia the tradeoffs between tracing and sampling of program execution.Dynamicmonitoring–basicrequirements.

         The usefulness of dynamic monitoring is demonstrated using a small ns2 project in Croatia version of the game, consisting of a user and a ship manager process executing on the Pyramid, and a queue manager process executing on a Sun workstation The ns2 project in Croatia monitoring system’s components are the central monitor, the PCS, and the AC executing on the Pyramid and the resident monitor executing on the Sun. This  demonstrates ns2 project in Croatia the dynamic, joint operation of the central and resident monitors with the AC and PCS. The purpose of this cooperation is to balance the rates of request generation by the user process and request processing by the ship manager. The monitoring statement ns2 project in Croatia instructs the monitor to notify the AC when the size of the request queue maintained by the queue manager process.

Ns2 project in Bulgaria

     Ns2 project in Bulgaria these measurements imply that a single resident monitor may fully utilize its processor if all other processors ns2 project in Bulgaria on the ten-node Encore Multimax generate events at the fastest possible rate. Similar results should hold for the -based Encore machines now in use.

     However, as with the ns2 project in Bulgaria real-time multiprocessor, excessive communication with the central monitor will result ilowutilization of the dedicated Encore node. We have observed similar results on a BBN Butterfly multiprocessor with another version of the monitoring system .

      To summarize, ns2 project in Bulgaria it appears that both the configuration of the monitoring system in terms of resident and central monitors and the selection of appropriate monitoring plans using probes ns2 project in Bulgaria and sensors, depend on the characteristics of the underlying hardware and on application characteristics or requirements stated with the attribute and view languages. It would be ns2 project in Bulgaria interesting to consider the automatic derivation of such application requirements from information supplied by the programming environment or by the ns2 project in Bulgaria adaptation controller This section describes a program monitoring and adaptation that highlights some of the design and implementation issues in distributed, dynamic monitoring.

      This example uses the Issos parallel programming environment This game shares ns2 project in Bulgaria one aspect with many parallel and distributed programs, including parallel branchand- bound applications , parallel MultiLisp programs , and others. Namely, the game is ns2 project in Bulgaria subject to problems with workload balancing, since the program dynamically generates and consumes units of work that cannot be predicted statically The game consists of ships moving on a sea.

Ns2 project in Vienna

      Ns2 project in Vienna this multiprocessor was composed of seven nodes, each containing an Intel  processor, which is somewhat slower than the Motorola  processors in our Sun- workstations. First, in this system, the relative ns2 project in vienna cost of sending messages within and among different processors is lower than in Unix. Specifically, the GEM real-time operating system executing on this multiprocessor provides ns2 project in Vienna  message sending primitives that can transmit small messages  within 1 ms, compared wit between somewhat faster Sun workstations. Second, this message ns2 project in Vienna communication overhead is roughly equivalent to the overhead of process switching in GEM .

      Third, the bandwidthof the bus connecting different ns2 project in Vienna multiprocessor nodes is quite high and generally underutilized  . Fourth, the multiprocessor’s link to the monitoring system’s user interface   has comparatively low bandwidth and ns2 project in Vienna high latency compared to the intra-multiprocessor links. Asa result, for this hardware configuration, we dedicated a single processor to the execution of a single resident monitor. Sensors and ns2 project in Vienna extended sensors send event records to this resident monitor at a cost of roughly ns2 project in Vienna per event record.

    The resident monitor performs all analyses not done by extended sensors and it also performs those analyses done by the central monitor in the distributed system  A similar monitoring architecture was adopted for an Encore Multimax multiprocessor, which could be used for execution of selected components of a parallel/distributed program ns2 project in Vienna mapped to a set of Sun workstations and the Encore Multimax . Here, a single Unix process acting as a resident monitor is responsible for all application processes executing on the Encore machine. ns2 project in Vienna this resident monitor sends event records to the central monitor executing on a Sun workstation, which may also communicate with resident monitors located on other Sun workstations.

ns2 project in berlin

      ns2 project in berlin thus, it is difficult to see how lazy matching can be folded into the object level match phase, or whether it is ns2 project in berlin desirable at all. The metarule matching method that one adopts is influenced by the considerations cited above. In the rest of this paper, we attempt to enumerate specific feasible techniques ns2 project in berlin and briefly outline their characteristics.- The first technique consists of compiling metarules into the object level matcher. This means that if one is using a RETE or TREAT ns2 project in berlin discrimination net matcher, for example, one can compile the metarule tests into the network.

     At the network nodes where final instance tokens are generated, one can insert ns2 project in berlin  additional test nodes, compiled from the metarules, and thus inhibit certain instances ns2 project in berlin from proceeding onward to the firing mechanism, i.e., redact them. This is practical when considering main memory based systems. Instances can simply be treated like any other token in this case If aggregate metarules are supported, however, we have several ns2 project in berlin problems. First, the network nodes storing instance tokens will likely grow very large especially when computing aggregate metarules. The performance of memory ns2 project ns2 project in berlin in berlin based systems would degrade significantly.

    Second an ‘Laggregate condition” to be tested at these nodes will have to be inhibited until all instances have been ns2 project in berlin computed. Thus, some means of determining when the match is completed and all instances have been computed is needed. This approach is essentially the same as the one proposed in. Now let’s consider base metarules for a moment in this context. The approach ns2 project in berlin is very straight.forward.

Ns2 project in Idaho

      Ns2 project in Idaho next, consider a different global event, which permits the system to use extended sensors for the event’s analysis. If the global event is then an extended sensor will generate events for the resident monitor only if its attribute’s ns2 project in Idaho respective value is , thereby reducing the total number of event records generated by the process This sensorbased analysis results in the lowest perturbation reported in the table above .

      Further ns 2project in Idaho reductions in perturbation may be achieved in several ways, including theuse of shared memory among user processes and the resident monitor to share ns2 project in Idaho monitoring information  the use of threads versus processes for representation of resident monitors , or the delivery of monitoring information across additional communication ns2 project in Idaho links among workstations, much like with the monitoring hardware additions in the Intel Paragom machine. In conclusion, the measurements reported in the table area simple illustration of the heuristic mentioned above: in the network ns2 project in Idaho environment, analysis should be moved as close to collection as possible.

     Note that this observation holds in computer networks, multicomputers  and multiprocessors, as long as the communication ns2 project in Idaho costs significantly outweigh the costs of the analysis being performed. We conjecture that this result will also hold for the monitoring hardware provided with the new Intel Paragom multicomputer, since its communication bandwidths are significantly lessthat the ns2project in Idaho computational power of the Intelused as a communication co-processor.An implementation of the monitor on a real-time multiprocessor system ns2 project in Idaho exhibits differences in several basic system parameters and therefore, dictates the use of different heuristics.

Ns2 project in manchester

     Ns2 project in Manchester at each event time, the process may elect to generate or not generate on actual event, where the generated event is an assignment of the value or  to ns2 project in Manchester a local variable mapped to a monitoring attributein the process  The global event to the evaluated by the monitoring system   The global event’s frequency of change for each program run is not known due to the randomness of the individual ns2 project in manchester event generators. In the measurements below, generator processes are first run without monitoring and then the event of interest is analyzed with extended sensors, by the resident monitor, or by the central monitor, respectively, each time measuring the ns2 project in Manchester resulting program perturbation.

       The table below depicts the measurement results In all cases above, the actual overhead reported here is dominated by the use of Unix communication ns2 project in Manchester primitives. Thus, the exact amounts of the reported overhead percentages is not relevant. Instead, observe the differences in the amounts reported above. Specifically, ns2 project in Manchester the entry “Unmonitored” depicts the total time in seconds for the unmonitored execution of two generating processes located on the same machine. The entry “Central” assumes ns2 project in Manchester the generation of event records by generator processes each time an actual assignment to attributel or attribute is performed.

      Those event ns2 project in Manchester records are then sent to the nonlocal central monitor  which compares the values of the respective attributes. Compared to the measurements in row “Central,” it is apparent that a comparison of attribute values using a resident monitor on the generators’ workstation is preferable to central monitoring This result holds despite the additional cost of context ns2 project in Manchester switching caused by the execution of the resident monitor on the generator processes’ workstation.

Ns2 project in liverpool

      Ns2 project in Liverpool while the full four-step process presented in the previous section may be automated, it can be be simplified significantly ns2 project in liverpool for particular hardware and software configurations. Inthis section, we present the plan simplifications used for the three hardware configurations on which the monitor has ns2 project in Liverpool been implementedThe first configuration is a local area network containing Sun  machines and a Pyramid communicating over an Ethernet . Asdiscussed in, communication in such an environment is very expensive compared with processing time. Hence, ns2 project in Liverpool for this configuration, we apply the following heuristic: push analyses to the lowest level where they may be performed, thereby reducing communication as much ns2 project in Liverpool as possible.

       This decision is motivated by the experimental results presented next, and is justified elsewhere Inparticular, this heuristic can be shown to minimize perturbation ns2 project in Liverpool and latency simultaneously for this configuration with all but artificially complex view specifications. This heuristic ensures that analyses of monitoring ns2 project in Liverpool information possible within the same address space in which the required sensors are located will be performed locally.

      A resident monitor performs the analysis that ns2 project in Liverpool requires event records collected from different processes on its node, and the central monitor performs the analysis that requires event records from multiple machines. The experimental results regarding the perturbation experienced in the distributed implementation of the monitoring system described next rely on a distributed workload generator. In the experiment below, the generator’s configuration consists of two event generator processes, both of which are collocated on a single Sun workstation. A resident monitor is also ns2 project in liverpool located on the workstation, but the central monitor resides on a different workstation on the same subnet. Each event generator process generates up to randomly drawn events.