PortableBatch System
Components of PBS
PBS consist of four majorcomponents: commands, the job Server, the job executor, and the job Scheduler.A brief description of each is given here.
Commands
PBS supplies both command linecommands and a graphical interface. These are used to submit, monitor, modify,and delete jobs. The commands can be installed on any system type supported byPBS and do not require the local presence of any of the other components ofPBS. There are three classifications of commands:
User commands: qsub, qstat, , qdel,qselect, qrerun, qorder, qmove, qhold, qalter, qmsg, qrls
Operator commands: qenable,qdisable, qrun, qstart, qstop, qterm
Administrator commands: qmgr,pbsnodes
Operator and administrator commandsrequire different access privileges.
Job Server
The Job Server is the central focusfor PBS. Within this document, it is generally referred to as the Server or bythe execution name pbs_server. All commands and the other daemons communicatewith the Server via an IP network. The Server's main function is to provide thebasic batch services such as receiving/creating a batch job, modifying the job,protecting the job against system crashes, and running the job (placing it intoexecution). One server manages one or more queues; a batch queue consists of acollection of zero or more batch jobs and a set of queue attributes. Jobs aresaid to reside in the queue or be members of the queue. In spite of the name,jobs residing in a queue need not be ordered first in, first out. Access to aqueue is limited to the server which owns the queue. All clients gaininformation about a queue or jobs within a queue through batch requests to theserver. Two main types of queues are defined: rouating queues and executionqueues. When a job resides in an execution queue, it is a candidate forexecution. A job in execution is still a member of the execution queue fromwhich it was selected for execution. When a job resides in a routing queue, itis a candidate for routing to a new destination. Each routing queue has a listof destinations to which jobs may be routed. The new destination may be adifferent queue within the same server or a queue under a different server. TheJob Server must know the list of nodes that can execute jobs: they are declaredin a file in the server private directory PBS_HOME/server_priv.
Job Executor
The job executor is the daemonwhich actually places the job into execution. This daemon, pbs_mom, isinformally called Mom as it is the mother of all executing jobs. Mom places ajob into execution when it receives a copy of the job from a Server. Momcreates a new session as identical to a user login session as is possible. Forexample, if the user's login shell is csh, then Mom creates a session in which.login is run as well as .cshrc. Mom also has the responsibility for returningthe job's output to the user when directed to do so by the Server. There mustbe a Mom running on every node that can execute jobs.
Job Scheduler
The Job Scheduler is another daemonwhich contains the site's policy controlling which job is run and where andwhen it is run. Because each site has its own ideas about what is a good oreffective policy, PBS allows each site to create its own Scheduler. When run,the Scheduler can communicate with the various Moms to learn about the state ofsystem resources and with the Server to learn about the availability of jobs toexecute. The interface to the Server is through the same API as the commands.In fact, the Scheduler just appears as a batch Manager to the Server.
Portable Batch System (or simplyPBS) is the name of computer software that performs job scheduling. Its primarytask is to allocate computational tasks, i.e., batch jobs, among the availablecomputing resources. It is often used in conjunction with UNIX clusterenvironments.
PBS is supported as a job schedulermechanism by several meta schedulers including Moab by Cluster Resources andGRAM (Grid Resource Allocation Manager), a component of the Globus
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SunJava Real-Time System
The Sun Java Real-Time System (Java RTS) is the first conformantcommercial implementation of Java Specification Request (JSR) -001, theReal-Time Specification for Java (RTSJ). Although initially released in 2002,the RTSJ was updated in July 2006 to include some new features which arecovered in this article.
Java RTS enables developers ofreal-time applications to take full advantage of Java while maintaining thepredictability of current real-time development platforms, such as QNX, andother, custom, embedded systems. With Java RTS, real-time components andnon-real-time components can coexist and share data on a single system. JavaRTS features are delivered via a separate real-time enabled version of the JavaVM. This VM can process both traditional Java SE components and Java RTScomponents, giving developers heretofore unforeseen flexibility. Sun offers anRTSJ-compliant Java VM that runs only on Solaris (both x86 and SPARC); whereasIBM offers one that runs on Linux with open-source real-time Linux extensions.
Real-TimeJava
Often, real-time applicationdevelopers will rely upon facilities within a real-time operating system,programming language, software framework, or a combination of all three, inorder to achieve real-time behavior in their applications. Examples of suchenvironments are QNX, VxWorks, Nucleus, and Solaris; each environment typicallycomes with tools and libraries for real-time application development.
Historically, Java has beendiscounted as a real-time language. This is due to the initial impression ofJava being slow in its early years. Besides the fact that real-time behavior isnot necessarily dependant on high performance, Java has come a long way interms of raw performance. With just-in-time (JIT) compilation, coupled with theSun HotSpot JVM, Java performance meets or exceeds that of similar applicationswritten in C/C++.
Sun's Java RTS is a separateimplementation of Java that meets both soft and hard real-time requirements andrequires a special JVM to run. However, Java RTS still maintains completecompatibility with existing Java SE 5 applications. In fact, it can runstandard Java SE applications in the same JVM alongside applications developedto use its real-time facilities. Tests have shown that Sun's Java RTS achievesmaximum latencies of 15 microseconds, with around 5 microseconds of jitter.Yes, that’s microseconds, not milliseconds!
KeYmaera:A Hybrid Theorem Prover for Hybrid Systems
KeYmaera is a hybrid verificationtool for hybrid systems that combines deductive, real algebraic, and computer algebraicprover technologies. It is an automated and interactive theorem prover for anatural specification and verification logic for hybrid systems. KeYmaerasupports differential dynamic logic (dL), which is a real-valued first-orderdynamic logic for hybrid programs, a program notation for hybrid automata. Forautomating the verification process, KeYmaera implements a generalizedfree-variable sequent calculus and automatic proof strategies that decomposethe hybrid system specification symbolically. To overcome the complexity ofreal arithmetic, we integrate real quantifier elimination following aniterative background closure strategy. Our tool is particularly suitable forverifying parametric hybrid systems and has been used successfully forverifying collision avoidance in case studies from train control, car control,and air traffic management.
In KeYmaera, verifying correctfunctioning of hybrid systems amounts to proving corresponding formulas in,what is called, differential dynamic logic dL. These formulas state the desiredcorrectness properties of the hybrid systems under consideration, includingsafety, liveness, reactivity, and controllability properties. For showing thatthese systems operate as expected, André Platzer has devised a logical verificationcalculus.
CrusoeSE Embedded System
86-compatible processors designedto optimize low power consumption and high-performance processing for a widerange of embedded applications.
The Transmeta Crusoe™ SpecialEmbedded (SE) TM5500 and TM5800 family of embedded processors are targeted athigh-performance, x86-compatible embedded processing applications.
PortableBatch System
Componentsof PBS
PBS consist of four majorcomponents: commands, the job Server, the job executor, and the job Scheduler.A brief description of each is given here.
Commands
PBS supplies both command linecommands and a graphical interface. These are used to submit, monitor, modify,and delete jobs. The commands can be installed on any system type supported byPBS and do not require the local presence of any of the other components ofPBS. There are three classifications of commands:
User commands: qsub, qstat, , qdel,qselect, qrerun, qorder, qmove, qhold, qalter, qmsg, qrls
Operator commands: qenable,qdisable, qrun, qstart, qstop, qterm
Administrator commands: qmgr,pbsnodes
ABECOMMInteractive Systems
ABECommunication and Multimedia Interactive Systems, also known as ABECOMM, is aprovider of various computerized software systems which focuses on businesssolutions. With our system engineers who have experienced working on the fieldhere and abroad, we promise to provide business solutions with highest level ofservice and satisfaction.
ABECOMM has a team that possessextensive experience in software engineering in the field of onlinecommunication, multimedia and business solutions that meets the servicerequirements of our clients here in the South East Asia, Middle East and inU.S.A.
ABECOMM commitments are to take thestress out of your hands. We are committed to provide tailored, high qualitycomputerized systems saving your time and means. With highly trainedprofessionals, we can augment our competency and at the same time reduce youreffort in solving different problems on your business operation.
SunJava Real-Time System
The Sun Java Real-Time System (Java RTS) is the first conformantcommercial implementation of Java Specification Request (JSR) -001, theReal-Time Specification for Java (RTSJ). Although initially released in 2002,the RTSJ was updated in July 2006 to include some new features which arecovered in this article.
Java RTS enables developers ofreal-time applications to take full advantage of Java while maintaining thepredictability of current real-time development platforms, such as QNX, andother, custom, embedded systems. With Java RTS, real-time components andnon-real-time components can coexist and share data on a single system. JavaRTS features are delivered via a separate real-time enabled version of the JavaVM. This VM can process both traditional Java SE components and Java RTScomponents, giving developers heretofore unforeseen flexibility. Sun offers anRTSJ-compliant Java VM that runs only on Solaris (both x86 and SPARC); whereasIBM offers one that runs on Linux with open-source real-time Linux extensions.
Real-TimeJava
Often, real-time applicationdevelopers will rely upon facilities within a real-time operating system,programming language, software framework, or a combination of all three, inorder to achieve real-time behavior in their applications. Examples of suchenvironments are QNX, VxWorks, Nucleus, and Solaris; each environment typicallycomes with tools and libraries for real-time application development.
KeYmaera:A Hybrid Theorem Prover for Hybrid Systems
KeYmaera is a hybrid verificationtool for hybrid systems that combines deductive, real algebraic, and computer algebraicprover technologies. It is an automated and interactive theorem prover for anatural specification and verification logic for hybrid systems. KeYmaerasupports differential dynamic logic (dL), which is a real-valued first-orderdynamic logic for hybrid programs, a program notation for hybrid automata. Forautomating the verification process, KeYmaera implements a generalizedfree-variable sequent calculus and automatic proof strategies that decomposethe hybrid system specification symbolically. To overcome the complexity ofreal arithmetic, we integrate real quantifier elimination following aniterative background closure strategy. Our tool is particularly suitable forverifying parametric hybrid systems and has been used successfully forverifying collision avoidance in case studies from train control, car control,and air traffic management.
CrusoeSE Embedded System
86-compatible processors designedto optimize low power consumption and high-performance processing for a widerange of embedded applications.
The Transmeta Crusoe™ SpecialEmbedded (SE) TM5500 and TM5800 family of embedded processors are targeted athigh-performance, x86-compatible embedded processing applications.
Embedded system developers can nowtake advantage of many of the key technology advances that have made Crusoe™processors popular in many ultra-light mobile computing devices such ashigh-performance operation, complete x86 instruction set compatibility,efficient computing for low power consumption, low voltage requirements and theability to design embedded systems without the need for a fan. With aperformance-per-watt ratio unmatched by any other processor in this marketsegment, Crusoe™ SE processors enable a new class of cost-effectivehigh-performance embedded designs.
Embedded system developers can nowtake advantage of many of the key technology advances that have made Crusoe™processors popular in many ultra-light mobile computing devices such ashigh-performance operation, complete x86 instruction set compatibility,efficient computing for low power consumption, low voltage requirements and theability to design embedded systems without the need for a fan. With aperformance-per-watt ratio unmatched by any other processor in this marketsegment, Crusoe™ SE processors enable a new class of cost-effectivehigh-performance embedded designs.
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