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  • Checking out systems programming, what should I learn, using what resources?

    - by Anto
    I have done some hobby application development, but now I'm interested in checking out systems programming (mainly operating systems, Linux kernel etc.). I know low-level languages like C, and I know minimal amounts of x86 Assembly (should I improve on it?). What resources/books/websites/projects etc. do you recommend for one to get started with systems programming and what topics are important? Note that I know close to nothing about the subject, so whatever resources you suggest should be introductory resources. I still know what the subject is and what it includes etc., but I have not done systems programming before (but some application development, as previously noted, and I'm familiar with a bunch of programming languages as well as software engineering in general and algorithms, data structures etc.).

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  • What are some good resources for learning about file systems? [closed]

    - by Daniel
    I'd like to learn about file system design at a very detailed level. I'm currently in a graduate level operating systems course, and we're currently going over file systems. We mostly discuss papers and such, but our semester long project is to implement a log-structured file system using fuse and a virtual disk. Are there any good books that focus heavily on file system design and implementation? I have some conceptual clouding on things that seem very basic such as "when we say that an inode has pointers to blocks, do we mean anything besides the inode keeping track of block numbers? Is there any other format for 'disk pointers'?" I'm actually looking at file system design to start my career, so I'm probably going to try to implement a more traditional file system with fuse and our virtual disk format after this course is over.

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  • Role of systems in entity systems architecture

    - by bio595
    I've been reading a lot about entity components and systems and have thought that the idea of an entity just being an ID is quite interesting. However I don't know how this completely works with the components aspect or the systems aspect. A component is just a data object managed by some relevant system. A collision system uses some BoundsComponent together with a spatial data structure to determine if collisions have happened. All good so far, but what if multiple systems need access to the same component? Where should the data live? An input system could modify an entities BoundsComponent, but the physics system(s) need access to the same component as does some rendering system. Also, how are entities constructed? One of the advantages I've read so much about is flexibility in entity construction. Are systems intrinsically tied to a component? If I want to introduce some new component, do I also have to introduce a new system or modify an existing one? Another thing that I've read often is that the 'type' of an entity is inferred by what components it has. If my entity is just an id how can I know that my robot entity needs to be moved or rendered and thus modified by some system? Sorry for the long post (or at least it seems so from my phone screen)!

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  • Design patterns frequently seen in embedded systems programming

    - by softwarelover
    I don't have any question related to coding. My concerns are about embedded systems programming independent of any particular programming language. Because I am new in the realm of embedded programming, I would quite appreciate responses from those who consider themselves experienced embedded systems programmers. I basically have 2 questions. Of the design patterns listed below are there any seen frequently in embedded systems programming? Abstraction-Occurrence pattern General Hierarchy pattern Player-Role pattern Singleton pattern Observer pattern Delegation pattern Adapter pattern Facade pattern Immutable pattern Read-Only Interface pattern Proxy pattern As an experienced embedded developer, what design patterns have you, as an individual, come across? There is no need to describe the details. Only the pattern names would suffice. Please share your own experience. I believe the answers to the above questions would work as a good starting point for any novice programmers in the embedded world.

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  • Full Portfolio of x86 Systems On Display at Oracle OpenWorld

    - by kgee
    This OpenWorld, Oracle’s x86 hardware team will have two hardware demos, showcasing the new X3 systems, as well as several other x86 solutions such as the ZFS Storage Appliance, Oracle Database Appliance and the Carrier Grade NETRA systems. These two demos are located in the South Hall in Oracle’s booth 1133 and Intel’s booth 1101.  The Intel booth will feature additional demos including 3D demos of each server, a static architectural demo, the Oracle x86 Grand Prix video game and the Intel Theatre featuring several presentations by Intel’s partners. Oracle’s Intel Theatre Schedule and Topics Include:Monday 1. 10:30 a.m. - Engineered to Work Together: Oracle x86 Systems in the Data Center2. 12:30 a.m. - The Oracle NoSQL Database on the Intel Platform.3. 1:30 p.m. - Accelerate Your Path to Cloud with Oracle VM4. 3:30 p.m. - Why Oracle Linux is the Best Linux for Your Intel Based Systems5. 4:30 p.m. - Accelerate Your Path to Cloud with Oracle VMTuesday 1. 10:00 a.m. - Speed of thought” Analytics using In-Memory Analytics2. 1:30 a.m. - A Storage Architecture for Big Data:  "It’s Not JUST Hadoop"3. 2:00 a.m. - Oracle Optimized Solution for Enterprise Cloud Infrastructure.4. 2:30 p.m. - Configuring Storage to Optimize Database Performance and Efficiency.5. 3:30 p.m. - Total Cloud Control for Oracle's x86 SystemsWednesday 1. 10:00 a.m. - Big Data Analysis Using R-Programming Language2. 11:30 a.m. - Extreme Performance Overview, The Oracle Exadata Database Machine3. 1:30 p.m. - Oracle Times Ten In-Memory Database Overview

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  • Enterprise vs Real time embedded systems

    - by JakeFisher
    In university I have 2 options for software architecture: Enterprise Real time embedded systems I would be very glad if someone can give me a brief explanation of what those are. I am interested in following criterias: Brief overview Complexity and interest. So does knowledge costs time? Area of usage Profit(salary) Working tools, programs. Might be some text editor, uml editor. Something else?

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  • Languages on embedded systems in aeronautic and spatial sector

    - by Niels
    I know that my question is very broad but a general answer would be nice. I would like to know which are the main languages used in aeronautic and spatial sector. I know that the OS which run on embedded systems are RTOS (Real time OS) and I think that, this languages must be checked correctly by different methods (formal methods, unit tests) and must permit a sure verification of whole process of a program.

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  • How to Avoid Your Next 12-Month Science Project

    - by constant
    While most customers immediately understand how the magic of Oracle's Hybrid Columnar Compression, intelligent storage servers and flash memory make Exadata uniquely powerful against home-grown database systems, some people think that Exalogic is nothing more than a bunch of x86 servers, a storage appliance and an InfiniBand (IB) network, built into a single rack. After all, isn't this exactly what the High Performance Computing (HPC) world has been doing for decades? On the surface, this may be true. And some people tried exactly that: They tried to put together their own version of Exalogic, but then they discover there's a lot more to building a system than buying hardware and assembling it together. IT is not Ikea. Why is that so? Could it be there's more going on behind the scenes than merely putting together a bunch of servers, a storage array and an InfiniBand network into a rack? Let's explore some of the special sauce that makes Exalogic unique and un-copyable, so you can save yourself from your next 6- to 12-month science project that distracts you from doing real work that adds value to your company. Engineering Systems is Hard Work! The backbone of Exalogic is its InfiniBand network: 4 times better bandwidth than even 10 Gigabit Ethernet, and only about a tenth of its latency. What a potential for increased scalability and throughput across the middleware and database layers! But InfiniBand is a beast that needs to be tamed: It is true that Exalogic uses a standard, open-source Open Fabrics Enterprise Distribution (OFED) InfiniBand driver stack. Unfortunately, this software has been developed by the HPC community with fastest speed in mind (which is good) but, despite the name, not many other enterprise-class requirements are included (which is less good). Here are some of the improvements that Oracle's InfiniBand development team had to add to the OFED stack to make it enterprise-ready, simply because typical HPC users didn't have the need to implement them: More than 100 bug fixes in the pieces that were not related to the Message Passing Interface Protocol (MPI), which is the protocol that HPC users use most of the time, but which is less useful in the enterprise. Performance optimizations and tuning across the whole IB stack: From Switches, Host Channel Adapters (HCAs) and drivers to low-level protocols, middleware and applications. Yes, even the standard HPC IB stack could be improved in terms of performance. Ethernet over IB (EoIB): Exalogic uses InfiniBand internally to reach high performance, but it needs to play nicely with datacenters around it. That's why Oracle added Ethernet over InfiniBand technology to it that allows for creating many virtual 10GBE adapters inside Exalogic's nodes that are aggregated and connected to Exalogic's IB gateway switches. While this is an open standard, it's up to the vendor to implement it. In this case, Oracle integrated the EoIB stack with Oracle's own IB to 10GBE gateway switches, and made it fully virtualized from the beginning. This means that Exalogic customers can completely rewire their server infrastructure inside the rack without having to physically pull or plug a single cable - a must-have for every cloud deployment. Anybody who wants to match this level of integration would need to add an InfiniBand switch development team to their project. Or just buy Oracle's gateway switches, which are conveniently shipped with a whole server infrastructure attached! IPv6 support for InfiniBand's Sockets Direct Protocol (SDP), Reliable Datagram Sockets (RDS), TCP/IP over IB (IPoIB) and EoIB protocols. Because no IPv6 = not very enterprise-class. HA capability for SDP. High Availability is not a big requirement for HPC, but for enterprise-class application servers it is. Every node in Exalogic's InfiniBand network is connected twice for redundancy. If any cable or port or HCA fails, there's always a replacement link ready to take over. This requires extra magic at the protocol level to work. So in addition to Weblogic's failover capabilities, Oracle implemented IB automatic path migration at the SDP level to avoid unnecessary failover operations at the middleware level. Security, for example spoof-protection. Another feature that is less important for traditional users of InfiniBand, but very important for enterprise customers. InfiniBand Partitioning and Quality-of-Service (QoS): One of the first questions we get from customers about Exalogic is: “How can we implement multi-tenancy?” The answer is to partition your IB network, which effectively creates many networks that work independently and that are protected at the lowest networking layer possible. In addition to that, QoS allows administrators to prioritize traffic flow in multi-tenancy environments so they can keep their service levels where it matters most. Resilient IB Fabric Management: InfiniBand is a self-managing network, so a lot of the magic lies in coming up with the right topology and in teaching the subnet manager how to properly discover and manage the network. Oracle's Infiniband switches come with pre-integrated, highly available fabric management with seamless integration into Oracle Enterprise Manager Ops Center. In short: Oracle elevated the OFED InfiniBand stack into an enterprise-class networking infrastructure. Many years and multiple teams of manpower went into the above improvements - this is something you can only get from Oracle, because no other InfiniBand vendor can give you these features across the whole stack! Exabus: Because it's not About the Size of Your Network, it's How You Use it! So let's assume that you somehow were able to get your hands on an enterprise-class IB driver stack. Or maybe you don't care and are just happy with the standard OFED one? Anyway, the next step is to actually leverage that InfiniBand performance. Here are the choices: Use traditional TCP/IP on top of the InfiniBand stack, Develop your own integration between your middleware and the lower-level (but faster) InfiniBand protocols. While more bandwidth is always a good thing, it's actually the low latency that enables superior performance for your applications when running on any networking infrastructure: The lower the latency, the faster the response travels through the network and the more transactions you can close per second. The reason why InfiniBand is such a low latency technology is that it gets rid of most if not all of your traditional networking protocol stack: Data is literally beamed from one region of RAM in one server into another region of RAM in another server with no kernel/drivers/UDP/TCP or other networking stack overhead involved! Which makes option 1 a no-go: Adding TCP/IP on top of InfiniBand is like adding training wheels to your racing bike. It may be ok in the beginning and for development, but it's not quite the performance IB was meant to deliver. Which only leaves option 2: Integrating your middleware with fast, low-level InfiniBand protocols. And this is what Exalogic's "Exabus" technology is all about. Here are a few Exabus features that help applications leverage the performance of InfiniBand in Exalogic: RDMA and SDP integration at the JDBC driver level (SDP), for Oracle Weblogic (SDP), Oracle Coherence (RDMA), Oracle Tuxedo (RDMA) and the new Oracle Traffic Director (RDMA) on Exalogic. Using these protocols, middleware can communicate a lot faster with each other and the Oracle database than by using standard networking protocols, Seamless Integration of Ethernet over InfiniBand from Exalogic's Gateway switches into the OS, Oracle Weblogic optimizations for handling massive amounts of parallel transactions. Because if you have an 8-lane Autobahn, you also need to improve your ramps so you can feed it with many cars in parallel. Integration of Weblogic with Oracle Exadata for faster performance, optimized session management and failover. As you see, “Exabus” is Oracle's word for describing all the InfiniBand enhancements Oracle put into Exalogic: OFED stack enhancements, protocols for faster IB access, and InfiniBand support and optimizations at the virtualization and middleware level. All working together to deliver the full potential of InfiniBand performance. Who else has 100% control over their middleware so they can develop their own low-level protocol integration with InfiniBand? Even if you take an open source approach, you're looking at years of development work to create, test and support a whole new networking technology in your middleware! The Extras: Less Hassle, More Productivity, Faster Time to Market And then there are the other advantages of Engineered Systems that are true for Exalogic the same as they are for every other Engineered System: One simple purchasing process: No headaches due to endless RFPs and no “Will X work with Y?” uncertainties. Everything has been engineered together: All kinds of bugs and problems have been already fixed at the design level that would have only manifested themselves after you have built the system from scratch. Everything is built, tested and integrated at the factory level . Less integration pain for you, faster time to market. Every Exalogic machine world-wide is identical to Oracle's own machines in the lab: Instant replication of any problems you may encounter, faster time to resolution. Simplified patching, management and operations. One throat to choke: Imagine finger-pointing hell for systems that have been put together using several different vendors. Oracle's Engineered Systems have a single phone number that customers can call to get their problems solved. For more business-centric values, read The Business Value of Engineered Systems. Conclusion: Buy Exalogic, or get ready for a 6-12 Month Science Project And here's the reason why it's not easy to "build your own Exalogic": There's a lot of work required to make such a system fly. In fact, anybody who is starting to "just put together a bunch of servers and an InfiniBand network" is really looking at a 6-12 month science project. And the outcome is likely to not be very enterprise-class. And it won't have Exalogic's performance either. Because building an Engineered System is literally rocket science: It takes a lot of time, effort, resources and many iterations of design/test/analyze/fix to build such a system. That's why InfiniBand has been reserved for HPC scientists for such a long time. And only Oracle can bring the power of InfiniBand in an enterprise-class, ready-to use, pre-integrated version to customers, without the develop/integrate/support pain. For more details, check the new Exalogic overview white paper which was updated only recently. P.S.: Thanks to my colleagues Ola, Paul, Don and Andy for helping me put together this article! var flattr_uid = '26528'; var flattr_tle = 'How to Avoid Your Next 12-Month Science Project'; var flattr_dsc = 'While most customers immediately understand how the magic of Oracle's Hybrid Columnar Compression, intelligent storage servers and flash memory make Exadata uniquely powerful against home-grown database systems, some people think that Exalogic is nothing more than a bunch of x86 servers, a storage appliance and an InfiniBand (IB) network, built into a single rack.After all, isn't this exactly what the High Performance Computing (HPC) world has been doing for decades?On the surface, this may be true. And some people tried exactly that: They tried to put together their own version of Exalogic, but then they discover there's a lot more to building a system than buying hardware and assembling it together. IT is not Ikea.Why is that so? Could it be there's more going on behind the scenes than merely putting together a bunch of servers, a storage array and an InfiniBand network into a rack? Let's explore some of the special sauce that makes Exalogic unique and un-copyable, so you can save yourself from your next 6- to 12-month science project that distracts you from doing real work that adds value to your company.'; var flattr_tag = 'Engineered Systems,Engineered Systems,Infiniband,Integration,latency,Oracle,performance'; var flattr_cat = 'text'; var flattr_url = 'http://constantin.glez.de/blog/2012/04/how-avoid-your-next-12-month-science-project'; var flattr_lng = 'en_GB'

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  • Operating systems theory -- using minimum number of semaphores

    - by stackuser
    This situation is prone to deadlock of processes in an operating system and I'd like to solve it with the minimum of semaphores. Basically there are three cooperating processes that all read data from the same input device. Each process, when it gets the input device, must read two consecutive data. I want to use mutual exclusion to do this. Semaphores should be used to synchronize: P1: P2: P3: input(a1,a2) input (b1,b2) input(c1,c2) Y=a1+c1 W=b2+c2 Z=a2+b1 Print (X) X=Z-Y+W The declaration and initialization that I think would work here are: semaphore s=1 sa1 = 0, sa2 = 0, sb1 = 0, sb2 = 0, sc1 = 0, sc2 = 0 I'm sure that any kernel programmers that happen on this can knock this out in a minute or 2. Diagram of cooperating Processes and one input device: It seems like P1 and P2 would start something like: wait(s) input (a1/b1, a2/b2) signal(s)

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  • Web application framework for embedded systems?

    - by datenwolf
    I'm currently developing the software for a measurement and control system. In addition to the usual SCPI interface I'd also give it a nice HTTP frontend. Now I don't want to reinvent the wheel all over again. I already have a simple HTTPD running, but I don't want to implement all the other stuff. So what I'm looking for is a web application toolkit targeted at embedded system development. In particular this has to run on a ARM Cortex-M4, and I have some 8k of RAM available for this. It must be written in C. Is there such a thing or do I have to implement this myself?

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  • Operating systems -- using minimum number of semaphores

    - by stackuser
    The three cooperating processes all read data from the same input device. Each process, when it gets the input device, must read two consecutive data. I want to use mutual exclusion to do this. The declaration and initialization that I think would work here are: semaphore s=1 sa1 = 0, sa2 = 0, sb1 = 0, sb2 = 0, sc1 = 0, sc2 = 0 I'd like to use semaphores to synchronize the following processes: P1: P2: P3: input(a1,a2) input (b1,b2) input(c1,c2) Y=a1+c1 W=b2+c2 Z=a2+b1 Print (X) X=Z-Y+W I'm wondering how to use the minimum number of semaphores to solve this. Diagram of cooperating Processes and one input device: It seems like P1 and P2 would start something like: wait(s) input (a1/b1, a2/b2) signal(s)

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  • Obscure Operating Systems

    - by DLH
    Do you ever get the urge to try random obscure operating systems? I think it's sometimes just fun to use systems that are not widely used. What obscure operating systems have you tried (or have thought about trying)? I've been looking into Haiku lately.

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  • two operating systems sharing their file systems with eachother (Windows and Linux)

    - by John Kube
    I have two operating systems installed on my notebook computer, Windows Vista and Ubuntu Linux. When I boot up, I'm presented with a bootloader which allows me to choose which one I want to load. I'm interested in sharing each operating system's file system with the other, such that I could access my Windows files from Linux and vice-versa. Is this possible, and if so how would one go about setting it up? Feel free to just post a link to an existing solution if there is one. I would Google for this myself, but I don't even know what to search for, as I don't know what this is called.

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  • How do I implement the bg, &, and fg commands functionaliity in my custom unix shell program written in C

    - by user1631009
    I am extending the functionality of a custom unix shell which I wrote as part of my lab assignment. It currently supports all commands through execvp calls, in-built commands like pwd, cd, history, echo and export, and also redirection and pipes. Now I wanted to add support for running a command in background e.g. $ls -la& I also want to implement bg and fg job control commands. I know this can be achieved if I execute the command by forking a new child process and not waiting for it in the parent process. But how do I again bring this command to foreground using fg? I have the idea of entering each background command in a list assigning each of them a serial number. But I don't know how do I make the processes execute in the background, then bring them back to foreground. I guess wait() and waitpid() system calls would come handy but I am not that comfortable with them. I tried reading the man pages but still am in the dark. Can someone please explain in a layman's language how to achieve this in UNIX system programming? And does it have something to do with SIGCONT and SIGSTP signals?

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  • How do I implement the bg, &, and bg commands functionaliity in my custom unix shell program written in C

    - by user1631009
    I am trying to extend the functionality of my custom unix shell which I earlier wrote as part of my lab assignment. It currently supports all commands through execvp calls, in-built commands like pwd, cd, history, echo and export, and also redirection and pipes. Now I wanted to add the support for running a command in background e.g. $ls -la& Now I also want to implement bg and fg job control commands. I know this can be achieved if I execute the command by forking a new child process and not waiting for it in the parent process. But how do I again bring this command to foreground using fg? I have the idea of entering each background command in a list assigning each of them a serial number. But I don't know how do I make the processes execute in the background, then bring them back to foreground. I guess wait() and waitpid() system calls would come handy but I am not that comfortable with them. I tried reading the man pages but still am in the dark. Can someone please explain in a layman's language how to achieve this in UNIX system programming? And does it have something to do with SIGCONT and SIGSTP signals?

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  • What are the advantages of programming to under an OS as opposed to bare metal executive?

    - by gby
    Assume you are presented with an embedded system application to program, in C, on a multi-core environment (think a Cavium or Tilera) and need to choose between two environments: Code the application under Linux in SMP mode or code the application under a thin bare metal executive (something like a very minimal RTOS), perhaps with a single core running UP Linux that can serve control tasks. For the purpose of this question, assume that both environment provide the same level of performance guarantees in any measurable aspects of run time performance, including number of meaningful action per second, jitter, latency, real time considerations - the works. (and yes, I realize this is by far not a trivial assumption at all, bare with me). How would you justify going with a Linux SMP based solution rather then a bare metal thin executive solution? The question may seems silly. It certainly seems obvious to me - but I have to convince someone that does not think the same. Could you help make a list of arguments in favor of choosing a real SMP aware OS (Linux) vs. a bare metal executive assuming performance guarantees are NOT an issue? Many thanks

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  • Which operating systems book is good as a quick refresher?

    - by rdasxy
    I am preparing for a technical interview and need to review the basics of major operating systems concepts. We used Tanenbaum's Modern Operating Systems in school for our operating systems course, which is a good book, but too long to be reviewed in the course of a few days. For an example, I am looking for what Programming Interviews Exposed is to Weiss's Data Structures & Algorithm Analysis. Any suggestions?

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  • Comparison between operational systems

    - by Gustavo Bandeira
    Some years ago, I've heard people saying that the OSX and Linux were better than Windows, I also remember of reading something that said the Solaris operating system didn't fragment their files and that the Linux file system was almost in the same step but none of these claims seemed to have basis or references. I got two questions: When comparing operating systems, what are the main points for comparison? How's the comparison between the main operating systems today?

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  • Why isn't SSL/TLS built into modern Operating Systems?

    - by Channel72
    A lot of the basic network protocols that make up the infrastructure of the Internet are built in to most major Operating Systems. Things like TCP, UDP, and DNS are all built into Linux, UNIX and Windows, and are made available to the programmer through low-level system APIs. But when it comes to SSL or TLS, one has to turn to a third-party library such as OpenSSL or Mozilla NSS. SSL is a relatively old protocol, and it's basically an industry standard as ubiquitous as TCP/IP, so why isn't it built into most Operating Systems?

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  • What route to take to become a systems developer?

    - by Ramin
    In the past I have done a lot of Java and Python coding. Mostly, I worked on web apps and some simple console or gui apps. I also have a formal education in computer science. What route should I take to become a systems developer? I always did like C++, but never had a chance to use it for anything. Would mastering C++ be one of the steps? If so what resources can you suggest? Also, I would like to know how much different is the work between plain old development and systems development. There seem to be a lot of overlapping between the two.

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  • Choice of operating systems for a Rackspace cloud installation

    - by riteshmnayak
    I am planning to use Rackspace cloud services to host a java web application and also run apace for wordpress and trac. What would be a stable operating system to host such an application. My requirements are that the core OS bundle should be minimalistic (so I can install only what I want), consume very little memory and be performant. I would also need it to contain softwares for the common lamp stack, J2EE stack etc. A supported package manager would be lovely. My choices are listed below. RHEL 5.3 or 5.4 Debian Lenny Ubuntu 8.04 onwards Centos 5.3 or 5.4 Arch 2009.02 Gentoo 2008.0 or 10.1 Fedora 11 or 12 PS: can somebody add the rackspace tag to this? Edit to remove this line as well. Thanks

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  • Advantages of Thread pooling in embedded systems

    - by Microkernel
    I am looking at the advantages of threadpooling design pattern in Embedded systems. I have listed few advantages, please go through them, comment and please suggest any other possible advantages that I am missing. Scalability in systems like ucos-2 where there is limit on number of threads. Increasing capability of any task when necessary like Garbage collection (say in normal systems if garbage collection is running under one task, its not possible to speed it up, but in threadpooling we can easily speed it up). Can set limit on the max system load. Please suggest if I am missing anything.

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  • Efficiently separating Read/Compute/Write steps for concurrent processing of entities in Entity/Component systems

    - by TravisG
    Setup I have an entity-component architecture where Entities can have a set of attributes (which are pure data with no behavior) and there exist systems that run the entity logic which act on that data. Essentially, in somewhat pseudo-code: Entity { id; map<id_type, Attribute> attributes; } System { update(); vector<Entity> entities; } A system that just moves along all entities at a constant rate might be MovementSystem extends System { update() { for each entity in entities position = entity.attributes["position"]; position += vec3(1,1,1); } } Essentially, I'm trying to parallelise update() as efficiently as possible. This can be done by running entire systems in parallel, or by giving each update() of one system a couple of components so different threads can execute the update of the same system, but for a different subset of entities registered with that system. Problem In reality, these systems sometimes require that entities interact(/read/write data from/to) each other, sometimes within the same system (e.g. an AI system that reads state from other entities surrounding the current processed entity), but sometimes between different systems that depend on each other (i.e. a movement system that requires data from a system that processes user input). Now, when trying to parallelize the update phases of entity/component systems, the phases in which data (components/attributes) from Entities are read and used to compute something, and the phase where the modified data is written back to entities need to be separated in order to avoid data races. Otherwise the only way (not taking into account just "critical section"ing everything) to avoid them is to serialize parts of the update process that depend on other parts. This seems ugly. To me it would seem more elegant to be able to (ideally) have all processing running in parallel, where a system may read data from all entities as it wishes, but doesn't write modifications to that data back until some later point. The fact that this is even possible is based on the assumption that modification write-backs are usually very small in complexity, and don't require much performance, whereas computations are very expensive (relatively). So the overhead added by a delayed-write phase might be evened out by more efficient updating of entities (by having threads work more % of the time instead of waiting). A concrete example of this might be a system that updates physics. The system needs to both read and write a lot of data to and from entities. Optimally, there would be a system in place where all available threads update a subset of all entities registered with the physics system. In the case of the physics system this isn't trivially possible because of race conditions. So without a workaround, we would have to find other systems to run in parallel (which don't modify the same data as the physics system), other wise the remaining threads are waiting and wasting time. However, that has disadvantages Practically, the L3 cache is pretty much always better utilized when updating a large system with multiple threads, as opposed to multiple systems at once, which all act on different sets of data. Finding and assembling other systems to run in parallel can be extremely time consuming to design well enough to optimize performance. Sometimes, it might even not be possible at all because a system just depends on data that is touched by all other systems. Solution? In my thinking, a possible solution would be a system where reading/updating and writing of data is separated, so that in one expensive phase, systems only read data and compute what they need to compute, and then in a separate, performance-wise cheap, write phase, attributes of entities that needed to be modified are finally written back to the entities. The Question How might such a system be implemented to achieve optimal performance, as well as making programmer life easier? What are the implementation details of such a system and what might have to be changed in the existing EC-architecture to accommodate this solution?

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  • Do different operating systems have different read and write speeds?

    - by Ivan
    If I have two different operating systems, such as Windows 8 and Ubuntu, running on the same hardware, will the two operating systems have different read and write speeds? My guess is that there would be minimal difference between operating systems and read and write speeds to the hard disk since the major limited factor is seeking; however, different operating systems may use different file systems in order to attempt to reduce seek time in the hard disk. Likewise, I'm sure that modern operating systems will not actually write directly to the hard disk, and instead will just have it in memory and marked with a dirty bit. Are there any studies that show differences in read and write speeds between OSs? Or would the file system being used by the OS matter more than the OS itself?

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