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  • Mark your calendar: Get ready for the next generation of the Oracle Database!

    - by Javier Puerta
    Mark your calendar for the following upcoming webcasts for partners on the new version of the Oracle Database: Oracle Database Technical Training Webcast for Partners: July 2nd, at 17:00 CET, 4:00 pm UK - Duration: 1 hour (Access details here) Oracle Database Sales Training Webcast for EMEA Partners: July 8th, at 10:00 am CET, 9am UK - Duration: 1 hour (Details will be communicated very soon)

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  • Ubuntu One Joomla 1.6 Component, for sharing content

    - by Chris Machens
    Hello, id like to support Ubuntu One, and enhance my project at http://biochar.me The website uses Joomla.org 1 of the most widely used CMS on the net and version 1.6 got released a few weeks ago. Now my question: Are there plans to deliver a component, to enhance the user experience for example with sharing files? http://joomlapolis.com releases their CB - Community Builder component for joomla on the 14th and for example a CB Plugin for Ubuntu One integration would be a great addition. Looking forward to your feedback.

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  • Windows Embedded Compact 7 CTP Released

    Microsoft today rolled out a community test preview (CTP) version of Windows Embedded Compact 7....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Meta package / quick reference for command line string manipulation tools?

    - by Dylan McCall
    The latest version of the Scribes text editor lets us select some text, hit Alt+X, and then run an arbitrary command. For example, I can run the sort command and the selected text is replaced appropriately. This is quite useful but I am also not very well-versed in awk and the like. Is there something I can grab that will provide more of these commands like sort? Maybe a package with a whole bunch of handy, task-specific string manipulation commands?

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  • Adobe sort Project Parfait, un outil en ligne pour extraire le CSS de votre PSD

    Adobe Project Parfait : extraire le CSS de votre PSDAdobe signe un bel outil qui promet de rendre de bons services aux webmaster en permettant d'extraire le code CSS d'un fichier PSD dans le navigateur. Dans le navigateur? C'est à dire que la version actuelle (beta) est gratuite et ne nécessite pas de posséder Photoshop pour l'utiliser.On peut imaginer que le webmaster a reçu la maquette d'une page en PSD qu'il lui suffit d'uploader sur Project Parfait pour en extraire le CSS.L'interface intuitive...

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  • unity bar not looking as supossed to

    - by Migue Garcia Ortiz
    hi everyone i'm still a newbie on linux ubuntu but there's a problem that's been bugging me and i haven't found an answer yet i recently upgrade from 12.04 to 12.10 and everything was fine but suddenly my pointer stop working and i was able to fix that however the menus on my computer started to look horrible like an old version of windows i'll leave a screenshot and i hope someone can help me thx in advance screenshot so you know what i'm talking about

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  • App Submission for Showdown

    - by Caustic
    If I submit my app to the ARB today, can I make any changes before Monday?. Or will the ARB consider my app based on the version that was submitted on the submission day? ie If I make changes will I have to resubmit. Obviously if they suggest changes I will have to resubmit. But what if there are no suggestions for change. Will they grab the latest versions of apps at the end of the competition time? Thanks

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  • Clouds Everywhere But not a Drop of Rain – Part 3

    - by sxkumar
    I was sharing with you how a broad-based transformation such as cloud will increase agility and efficiency of an organization if process re-engineering is part of the plan.  I have also stressed on the key enterprise requirements such as “broad and deep solutions, “running your mission critical applications” and “automated and integrated set of capabilities”. Let me walk you through some key cloud attributes such as “elasticity” and “self-service” and what they mean for an enterprise class cloud. I will also talk about how we at Oracle have taken a very enterprise centric view to developing cloud solutions and how our products have been specifically engineered to address enterprise cloud needs. Cloud Elasticity and Enterprise Applications Requirements Easy and quick scalability for a short-period of time is the signature of cloud based solutions. It is this elasticity that allows you to dynamically redistribute your resources according to business priorities, helps increase your overall resource utilization, and reduces operational costs by allowing you to get the most out of your existing investment. Most public clouds are offering a instant provisioning mechanism of compute power (CPU, RAM, Disk), customer pay for the instance-hours(and bandwidth) they use, adding computing resources at peak times and removing them when they are no longer needed. This type of “just-in-time” serving of compute resources is well known for mid-tiers “state less” servers such as web application servers and web servers that just need another machine to start and run on it but what does it really mean for an enterprise application and its underlying data? Most enterprise applications are not as quite as “state less” and justifiably so. As such, how do you take advantage of cloud elasticity and make it relevant for your enterprise apps? This is where Cloud meets Grid Computing. At Oracle, we have invested enormous amount of time, energy and resources in creating enterprise grid solutions. All our technology products offer built-in elasticity via clustering and dynamic scaling. With products like Real Application Clusters (RAC), Automatic Storage Management, WebLogic Clustering, and Coherence In-Memory Grid, we allow all your enterprise applications to benefit from Cloud elasticity –both vertically and horizontally - without requiring any application changes. A number of technology vendors take a rather simplistic route of starting up additional or removing unneeded VM as the "Cloud Scale-Out" solution. While this may work for stateless mid-tier servers where load balancers can handle the addition and remove of instances transparently but following a similar approach for the database tier - often called as "database sharding" - requires significant application modification and typically does not work with off the shelf packaged applications. Technologies like Oracle Database Real Application Clusters, Automatic Storage Management, etc. on the other hand bring the benefits of incremental scalability and on-demand elasticity to ANY application by providing a simplified abstraction layers where the application does not need deal with data spread over multiple database instances. Rather they just talk to a single database and the database software takes care of aggregating resources across multiple hardware components. It is the technologies like these that truly make a cloud solution relevant for enterprises.  For customers who are looking for a next generation hardware consolidation platform, our engineered systems (e.g. Exadata, Exalogic) not only provide incredible amount of performance and capacity, they also reduce the data center complexity and simplify operations. Assemble, Deploy and Manage Enterprise Applications for Cloud Products like Oracle Virtual assembly builder (OVAB) resolve the complex problem of bringing the cloud speed to complex multi-tier applications. With assemblies, you can not only provision all components of a multi-tier application and wire them together by push of a button, other aspects of application lifecycle, such as real-time application testing, scale-up/scale-down, performance and availability monitoring, etc., are also automated using Oracle Enterprise Manager.  An essential criteria for an enterprise cloud to succeed is the ability to ensure business service levels especially when business users have either full visibility on the usage cost with a “show back” or a “charge back”. With Oracle Enterprise Manager 12c, we have created the most comprehensive cloud management solution in the industry that is capable of managing business service levels “applications-to-disk” in a enterprise private cloud – all from a single console. It is the only cloud management platform in the industry that allows you to deliver infrastructure, platform and application cloud services out of the box. Moreover, it offers integrated and complete lifecycle management of the cloud - including planning and set up, service delivery, operations management, metering and chargeback, etc .  Sounds unbelievable? Well, just watch this space for more details on how Oracle Enterprise Manager 12c is the nerve center of Oracle Cloud! Our cloud solution portfolio is also the broadest and most deep in the industry  - covering public, private, hybrid, Infrastructure, platform and applications clouds. It is no coincidence therefore that the Oracle Cloud today offers the most comprehensive set of public cloud services in the industry.  And to a large part, this has been made possible thanks to our years on investment in creating cloud enabling technologies.  Summary  But the intent of this blog post isn't to dwell on how great our solutions are (these are just some examples to illustrate how we at Oracle have approached this problem space). Rather it is to help you ask the right questions before you embark on your cloud journey.  So to summarize, here are the key takeaways.       It is critical that you are clear on why you are building the cloud. Successful organizations keep business benefits as the first and foremost cloud objective. On the other hand, those who approach this purely as a technology project are more likely to fail. Think about where you want to be in 3-5 years before you get started. Your long terms objectives should determine what your first step ought to be. As obvious as it may seem, more people than not make the first move without knowing where they are headed.  Don’t make the mistake of equating cloud to virtualization and Infrastructure-as-a-Service (IaaS). Spinning a VM on-demand will give some short term relief to your IT staff but is unlikely to solve your larger business problems. As such, even if IaaS is your first step towards a more comprehensive cloud, plan the roadmap around those higher level services before you begin. And ask your vendors on how they are going to be your partners in this journey. Capabilities like self-service access and chargeback/showback are absolutely critical if you really expect your cloud to be transformational. Your business won't see the full benefits of the cloud until it empowers them with same kind of control and transparency that they are used to while using a public cloud service.  Evaluate the benefits of integration, as opposed to blindly following the best-of-breed strategy. Integration is a huge challenge and more so in a cloud environment. There are enormous costs associated with stitching a solution out of disparate components and even more in maintaining it. Hope you found these ideas helpful. Looking forward to hearing your thoughts and experiences.

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  • Adobe Creative Cloud : la Creative Suite piratée quand même, le nouveau Dreamweaver proposé illégalement un jour après sa sortie

    Adobe Creative Cloud : la Creative Suite piratée quand même Les nouveaux Dreamweaver et Photoshop proposés illégalement un jour après leur sortieLe Cloud n'y a pas changé grand-chose. Le choix d'Adobe de ne plus commercialiser de versions « en boite » de ses produits mais uniquement une version sur abonnement, Creative Cloud, n'aura tenu les pirates en respect que quelques heures.En fin de la semaine dernière, la presse spécialisée américaine a en effet remarqué que les premiers torrent de la Creative Suite étaient apparus sur le célèbre annuaire The Pirate Bay.Ces versions piratées ne demandent pas d'authentification via le site ...

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  • Sortie de KDE 4.6 : le nouvel environnement de bureau Linux vise les tablettes et l'embarqué

    Sortie de KDE 4.6 L'environnement de bureau vise les tablettes et l'embarqué Mise à jour du 31/01/11 La nouvelle version de l'environnement de bureau KDE vient de sortir. « Beaucoup de travail a été fait pour améliorer ses performances et sa stabilité », écrit l'équipe de développement dans sa présentation des nouveautés. Avec KDE 4.6, l'accent a été mis sur la mobilité et les systèmes embarqués « en modularisant encore plus les librairies ». « Réduire les dépendances entre librairies et permettre à certaines fonctionnalités d'être désactivées permet aux frameworks KDE d'être à présent facilement déployés sur l...

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  • NetCAT ou le lancement des tests des dernières builds de NetBeans 6.9 : Dernière ligne droite pour l

    NetCAT ou le lancement des tests des dernières build de NetBeans 6.9 Dernière ligne droite pour la nouvelle mouture de NetBeans Depuis le 15 Mars, NetCAT (NetBeans Community Acceptance Testing program), a débuté la série de tests des dernières versions builds de la plateforme NetBeans. Ainsi, une cinquantaine de membres ayant demandé leur intégration au projet vont tester et émettre des retours d'expérience afin d'améliorer le maximum de points dans l'objectif d'obtenir une version finale stable et sans bugs. Le programme va se dérouler pendant 3 mois autour des milestones de l'IDE Voici le planning prévu : [IMG]http://www.livesphere.fr/images/dvp/netc...

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  • WebLogic Silent Install 11.1.1.4 (WLS 10.3.4)

    - by john.graves(at)oracle.com
    This is just a quick note to remind myself of how incredibly easy it is to install the base products without the aid of a mouse! Note to Windoze users: Why?!?!  I’m only showing Linux examples in this blog so I encourage you to just say NO to win-no-z  install.sh !/bin/bash ./wls1034_oepe111161_linux32.bin -mode=silent -silent_xml=./silent.xml silent.xml <?xml version="1.0" encoding="UTF-8"?> <bea-installer> <input-fields> <data-value name="BEAHOME" value="/opt/app/wls10.3.4" /> <data-value name="WLS_INSTALL_DIR" value="/opt/app/wls10.3.4/wlserver_10.3" /> </input-fields> </bea-installer> .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Note about Oracle_Home: Since all products are moving to a common WLS base, I simply use the WLS version as my Oracle Home.  In this case wls10.3.4.  Also, I keep my user_projects outside my Oracle_Home directory to keep things clean.  I typically use /opt/app/user_projects or a variation of that.

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  • Unable to run curl on on Ubuntu11.10

    - by ryy
    I ran : sudo apt-get install curl libcurl3 libcurl3-dev php5-curl Put: extension=php_curl.so in both /etc/php5/cli/php.ini and /etc/php5/apache2/php.ini But running php from the command line gives me the following error: PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php5/20090626+lfs/php_curl.so' - /usr/lib/php5/20090626+lfs/php_curl.so: cannot open shared object file: No such file or directory in Unknown on line 0 Running the install commands again tells me that everything is already the newest version. Running: locate php_curl.so Returns nothing.

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  • Transmission stopped working, says it's not installed even though it is

    - by Bodhidarma
    So transmission decided to randomly stop working. When I click on torrents transmission comes up as an option, but when I click ok nothing happens. When I go to the terminal and try to open transmission it tells me it's not installed. it recommends I install it with sudo apt-get install transmission-gtk. When I do this it says something like "transmission already newest version." So it's installed, clearly. Somebodddy help!

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  • Dell Inspiron 15R 5520 Wireless Device Not Detected

    - by ashish
    I bought a Dell Inspiron 5520 15R last week and I am a newbie in Ubuntu platform. I installed Windows 7 as well as Ubuntu 12.04 64-bit. But my wireless device is not detected in Ubuntu while it is working fine in Windows OS. My wireless device is Dell Wireless 1704 802.11B 2.4GHZ. Is this a compatibility problem with Ubuntu. What would be the solution? Do I need to install another version of Ubuntu?

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  • Interim Patches for CVE-2011-4313 released through MOS

    - by Alan
    As reported on the article on the Sun Security Blog, interim patches are available for Solaris 8,9 and 10 directly from MOS without the need to log a Service Request. There is also Interim Relief available for Solaris 11, but at this point in time that will still require a Service Request. As seen from running "named -V", these patches implement the same fix as ISC by taking Bind to the version:BIND 9.6-ESV-R5-P1.

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  • BIDS Helper 1.6 Beta Release (now with SQL 2012 support!)

    - by Darren Gosbell
    The beta for BIDS Helper 1.6 was just released. We have not updated the version notification just yet as we would like to get some feedback on people's experiences with the SQL 2012 version. So if you are using SQL 2012, go grab it and let us know how you go (you can post a comment on this blog post or on the BIDS Helper site itself). This is the first release that supports SQL 2012 and consequently also the first release that runs in Visual Studio 2010. A big thanks to Greg Galloway for doing the bulk of the work on this release. Please note that if you are doing an xcopy deploy that you will need to unblock the files you download or you will get a cryptic error message. This appears to be caused by a security update to either Visual Studio or the .Net framework – the xcopy deploy instructions have been updated to show you how to do this. Below are the notes from the release page. ====== This beta release is the first to support SQL Server 2012 (in addition to SQL Server 2005, 2008, and 2008 R2). Since it is marked as a beta release, we are looking for bug reports in the next few months as you use BIDS Helper on real projects. In addition to getting all existing BIDS Helper functionality working appropriately in SQL Server 2012 (SSDT), the following features are new... Analysis Services Tabular Smart Diff Tabular Actions Editor Tabular HideMemberIf Tabular Pre-Build Fixes and Updates The Unused Datasets feature for Reporting Services now accounts for new features in Reporting Services 2008 R2 like Lookups and new features in Reporting Services 2012. SSIS: emit an informational message when a variable has an expression defined and EvaluateAsExpression = False SSAS: roles reports points to wrong server SSIS - Variable Copy / Move broken in v1.5 "Unused DataSets Report" not showing up in Context menu on VS2005 if Solution Folders used SSAS Tabular: Create a UI for managing actions SSAS Tabular: Smart Diff improvements for new schema and Tabular models SSIS: Copy/Move Variable Erroring due to custom Control Flow item Icon SSIS Performance Visualization Index out of range fixing bugs in AggManager when aggregation design IDs don't match names The exe downloads are a self extracting installer, the zip downloads allow for an xcopy deploy. Make sure to note the updated xcopy deploy instructions for SQL Server 2012.

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  • Use Expressions with LINQ to Entities

    - by EltonStoneman
    [Source: http://geekswithblogs.net/EltonStoneman] Recently I've been putting together a generic approach for paging the response from a WCF service. Paging changes the service signature, so it's not as simple as adding a behavior to an existing service in config, but the complexity of the paging is isolated in a generic base class. We're using the Entity Framework talking to SQL Server, so when we ask for a page using LINQ's .Take() method we get a nice efficient SQL query for just the rows we want, with minimal impact on SQL Server and network traffic. We use the maximum ID of the record returned as a high-water mark (rather than using .Skip() to go to the next record), so the approach caters for records being deleted between page requests. In the paged response we include a HasMorePages indicator, computed by comparing the max ID in the page of results to the max ID for the whole resultset - if the latter is bigger, then there are more pages. In some quick performance testing, the paged version of the service performed much more slowly than the unpaged version, which was unexpected. We narrowed it down to the code which gets the max ID for the full resultset - instead of building an efficient MAX() SQL query, EF was returning the whole resultset and then computing the max ID in the service layer. It's easy to reproduce - take this AdventureWorks query:             var context = new AdventureWorksEntities();             var query = from od in context.SalesOrderDetail                         where od.ModifiedDate >= modified                          && od.SalesOrderDetailID.CompareTo(id) > 0                         orderby od.SalesOrderDetailID                         select od;   We can find the maximum SalesOrderDetailID like this:             var maxIdEfficiently = query.Max(od => od.SalesOrderDetailID);   which produces our efficient MAX() SQL query. If we're doing this generically and we already have the ID function in a Func:             Func<SalesOrderDetail, int> idFunc = od => od.SalesOrderDetailID;             var maxIdInefficiently = query.Max(idFunc);   This fetches all the results from the query and then runs the Max() function in code. If you look at the difference in Reflector, the first call passes an Expression to the Max(), while the second call passes a Func. So it's an easy fix - wrap the Func in an Expression:             Expression<Func<SalesOrderDetail, int>> idExpression = od => od.SalesOrderDetailID;             var maxIdEfficientlyAgain = query.Max(idExpression);   - and we're back to running an efficient MAX() statement. Evidently the EF provider can dissect an Expression and build its equivalent in SQL, but it can't do that with Funcs.

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  • Quick Tip - Speed a Slow Restore from the Transaction Log

    - by KKline
    Here's a quick tip for you: During some restore operations on Microsoft SQL Server, the transaction log redo step might be taking an unusually long time. Depending somewhat on the version and edition of SQL Server you've installed, you may be able to increase performance by tinkering with the readahead performance for the redo operations. To do this, you should use the MAXTRANSFERSIZE parameter of the RESTORE statement. For example, if you set MAXTRANSFERSIZE=1048576, it'll use 1MB buffers. If you...(read more)

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  • Library For Opengl 1.4?

    - by Robinson Joaquin
    My netbook only supports openGL version 1.4, my GPU is intel gma 3150, so for you what is the best library/tools to use or somewhat great move to make/advice, there are no wrong answers, (I am trying to create a game) PS: I already check the net for resources but, opengl (redbook) 4th edition is scarce (and redbook for v1.1 is already deprecated and is very OLD than what I'm looking for), besides I don't have money to buy a new laptop or a opengl book from online shop because international delivery is very expensive, I'm from outside US.

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  • Why do old programming languages continue to be revised?

    - by SunAvatar
    This question is not, "Why do people still use old programming languages?" I understand that quite well. In fact the two programming languages I know best are C and Scheme, both of which date back to the 70s. Recently I was reading about the changes in C99 and C11 versus C89 (which seems to still be the most-used version of C in practice and the version I learned from K&R). Looking around, it seems like every programming language in heavy use gets a new specification at least once per decade or so. Even Fortran is still getting new revisions, despite the fact that most people using it are still using FORTRAN 77. Contrast this with the approach of, say, the typesetting system TeX. In 1989, with the release of TeX 3.0, Donald Knuth declared that TeX was feature-complete and future releases would contain only bug fixes. Even beyond this, he has stated that upon his death, "all remaining bugs will become features" and absolutely no further updates will be made. Others are free to fork TeX and have done so, but the resulting systems are renamed to indicate that they are different from the official TeX. This is not because Knuth thinks TeX is perfect, but because he understands the value of a stable, predictable system that will do the same thing in fifty years that it does now. Why do most programming language designers not follow the same principle? Of course, when a language is relatively new, it makes sense that it will go through a period of rapid change before settling down. And no one can really object to minor changes that don't do much more than codify existing pseudo-standards or correct unintended readings. But when a language still seems to need improvement after ten or twenty years, why not just fork it or start over, rather than try to change what is already in use? If some people really want to do object-oriented programming in Fortran, why not create "Objective Fortran" for that purpose, and leave Fortran itself alone? I suppose one could say that, regardless of future revisions, C89 is already a standard and nothing stops people from continuing to use it. This is sort of true, but connotations do have consequences. GCC will, in pedantic mode, warn about syntax that is either deprecated or has a subtly different meaning in C99, which means C89 programmers can't just totally ignore the new standard. So there must be some benefit in C99 that is sufficient to impose this overhead on everyone who uses the language. This is a real question, not an invitation to argue. Obviously I do have an opinion on this, but at the moment I'm just trying to understand why this isn't just how things are done already. I suppose the question is: What are the (real or perceived) advantages of updating a language standard, as opposed to creating a new language based on the old?

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 4

    - by MarkPearl
    Learning Outcomes Explain the characteristics of memory systems Describe the memory hierarchy Discuss cache memory principles Discuss issues relevant to cache design Describe the cache organization of the Pentium Computer Memory Systems There are key characteristics of memory… Location – internal or external Capacity – expressed in terms of bytes Unit of Transfer – the number of bits read out of or written into memory at a time Access Method – sequential, direct, random or associative From a users perspective the two most important characteristics of memory are… Capacity Performance – access time, memory cycle time, transfer rate The trade off for memory happens along three axis… Faster access time, greater cost per bit Greater capacity, smaller cost per bit Greater capacity, slower access time This leads to people using a tiered approach in their use of memory   As one goes down the hierarchy, the following occurs… Decreasing cost per bit Increasing capacity Increasing access time Decreasing frequency of access of the memory by the processor The use of two levels of memory to reduce average access time works in principle, but only if conditions 1 to 4 apply. A variety of technologies exist that allow us to accomplish this. Thus it is possible to organize data across the hierarchy such that the percentage of accesses to each successively lower level is substantially less than that of the level above. A portion of main memory can be used as a buffer to hold data temporarily that is to be read out to disk. This is sometimes referred to as a disk cache and improves performance in two ways… Disk writes are clustered. Instead of many small transfers of data, we have a few large transfers of data. This improves disk performance and minimizes processor involvement. Some data designed for write-out may be referenced by a program before the next dump to disk. In that case the data is retrieved rapidly from the software cache rather than slowly from disk. Cache Memory Principles Cache memory is substantially faster than main memory. A caching system works as follows.. When a processor attempts to read a word of memory, a check is made to see if this in in cache memory… If it is, the data is supplied, If it is not in the cache, a block of main memory, consisting of a fixed number of words is loaded to the cache. Because of the phenomenon of locality of references, when a block of data is fetched into the cache, it is likely that there will be future references to that same memory location or to other words in the block. Elements of Cache Design While there are a large number of cache implementations, there are a few basic design elements that serve to classify and differentiate cache architectures… Cache Addresses Cache Size Mapping Function Replacement Algorithm Write Policy Line Size Number of Caches Cache Addresses Almost all non-embedded processors support virtual memory. Virtual memory in essence allows a program to address memory from a logical point of view without needing to worry about the amount of physical memory available. When virtual addresses are used the designer may choose to place the cache between the MMU (memory management unit) and the processor or between the MMU and main memory. The disadvantage of virtual memory is that most virtual memory systems supply each application with the same virtual memory address space (each application sees virtual memory starting at memory address 0), which means the cache memory must be completely flushed with each application context switch or extra bits must be added to each line of the cache to identify which virtual address space the address refers to. Cache Size We would like the size of the cache to be small enough so that the overall average cost per bit is close to that of main memory alone and large enough so that the overall average access time is close to that of the cache alone. Also, larger caches are slightly slower than smaller ones. Mapping Function Because there are fewer cache lines than main memory blocks, an algorithm is needed for mapping main memory blocks into cache lines. The choice of mapping function dictates how the cache is organized. Three techniques can be used… Direct – simplest technique, maps each block of main memory into only one possible cache line Associative – Each main memory block to be loaded into any line of the cache Set Associative – exhibits the strengths of both the direct and associative approaches while reducing their disadvantages For detailed explanations of each approach – read the text book (page 148 – 154) Replacement Algorithm For associative and set associating mapping a replacement algorithm is needed to determine which of the existing blocks in the cache must be replaced by a new block. There are four common approaches… LRU (Least recently used) FIFO (First in first out) LFU (Least frequently used) Random selection Write Policy When a block resident in the cache is to be replaced, there are two cases to consider If no writes to that block have happened in the cache – discard it If a write has occurred, a process needs to be initiated where the changes in the cache are propagated back to the main memory. There are several approaches to achieve this including… Write Through – all writes to the cache are done to the main memory as well at the point of the change Write Back – when a block is replaced, all dirty bits are written back to main memory The problem is complicated when we have multiple caches, there are techniques to accommodate for this but I have not summarized them. Line Size When a block of data is retrieved and placed in the cache, not only the desired word but also some number of adjacent words are retrieved. As the block size increases from very small to larger sizes, the hit ratio will at first increase because of the principle of locality, which states that the data in the vicinity of a referenced word are likely to be referenced in the near future. As the block size increases, more useful data are brought into cache. The hit ratio will begin to decrease as the block becomes even bigger and the probability of using the newly fetched information becomes less than the probability of using the newly fetched information that has to be replaced. Two specific effects come into play… Larger blocks reduce the number of blocks that fit into a cache. Because each block fetch overwrites older cache contents, a small number of blocks results in data being overwritten shortly after they are fetched. As a block becomes larger, each additional word is farther from the requested word and therefore less likely to be needed in the near future. The relationship between block size and hit ratio is complex, and no set approach is judged to be the best in all circumstances.   Pentium 4 and ARM cache organizations The processor core consists of four major components: Fetch/decode unit – fetches program instruction in order from the L2 cache, decodes these into a series of micro-operations, and stores the results in the L2 instruction cache Out-of-order execution logic – Schedules execution of the micro-operations subject to data dependencies and resource availability – thus micro-operations may be scheduled for execution in a different order than they were fetched from the instruction stream. As time permits, this unit schedules speculative execution of micro-operations that may be required in the future Execution units – These units execute micro-operations, fetching the required data from the L1 data cache and temporarily storing results in registers Memory subsystem – This unit includes the L2 and L3 caches and the system bus, which is used to access main memory when the L1 and L2 caches have a cache miss and to access the system I/O resources

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