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Search found 156 results on 7 pages for 'multicore'.

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  • Are indivisible operations still indivisible on multiprocessor and multicore systems?

    - by Steve314
    As per the title, plus what are the limitations and gotchas. For example, on x86 processors, alignment for most data types is optional - an optimisation rather than a requirement. That means that a pointer may be stored at an unaligned address, which in turn means that pointer might be split over a cache page boundary. Obviously this could be done if you work hard enough on any processor (picking out particular bytes etc), but not in a way where you'd still expect the write operation to be indivisible. I seriously doubt that a multicore processor can ensure that other cores can guarantee a consistent all-before or all-after view of a written pointer in this unaligned-write-crossing-a-page-boundary situation. Am I right? And are there any similar gotchas I haven't thought of?

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  • Python: how to run several scripts (or functions) at the same time under windows 7 multicore processor 64bit

    - by Gianni
    sorry for this question because there are several examples in Stackoverflow. I am writing in order to clarify some of my doubts because I am quite new in Python language. i wrote a function: def clipmyfile(inFile,poly,outFile): ... # doing something with inFile and poly and return outFile Normally I do this: clipmyfile(inFile="File1.txt",poly="poly1.shp",outFile="res1.txt") clipmyfile(inFile="File2.txt",poly="poly2.shp",outFile="res2.txt") clipmyfile(inFile="File3.txt",poly="poly3.shp",outFile="res3.txt") ...... clipmyfile(inFile="File21.txt",poly="poly21.shp",outFile="res21.txt") I had read in this example Run several python programs at the same time and i can use (but probably i wrong) from multiprocessing import Pool p = Pool(21) # like in your example, running 21 separate processes to run the function in the same time and speed my analysis I am really honest to say that I didn't understand the next step. Thanks in advance for help and suggestion Gianni

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  • Optimal Sharing of heavy computation job using Snow and/or multicore

    - by James
    Hi, I have the following problem. First my environment, I have two 24-CPU servers to work with and one big job (resampling a large dataset) to share among them. I've setup multicore and (a socket) Snow cluster on each. As a high-level interface I'm using foreach. What is the optimal sharing of the job? Should I setup a Snow cluster using CPUs from both machines and split the job that way (i.e. use doSNOW for the foreach loop). Or should I use the two servers separately and use multicore on each server (i.e. split the job in two chunks, run them on each server and then stich it back together). Basically what is an easy way to: 1. Keep communication between servers down (since this is probably the slowest bit). 2. Ensure that the random numbers generated in the servers are not highly correlated.

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  • Solr Multicore Admin Problem

    - by Daniel M
    Im trying to add a url based security constraint to solr deployed in websphere 6.1. If I specify the core name in the url of the constraint then the admin url for that core gives a 404. Has anyone had any success with this or any suggestions? Cheers Cross-posted with stackoverflow

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  • Multicore solr on Ubuntu 10.04 working for anyone?

    - by coleifer
    Following instructions from the two sites below, I've installed tomcat6 and solr 1.4 http://gist.github.com/204638 https://wiki.fourkitchens.com/display/TECH/Solr+1.4+on+Ubuntu+9.10+and+CentOS+5 I have successfully got it up and running on a server running 9.04 with multicore support, but on the 10.04 I can't seem to get it to work. I am able to reach localhost:xxxx/solr/ on the 10.04 box and see a single link to the Solr Admin, but following the link takes me to a 404 page with the following output: /solr/admin/ HTTP Status 404 - missing core name in path The requested resource (missing core name in path) is not available I am also unable to access /solr/site1/ as I would except - it similarly returns a 404 <!-- from /var/solr/solr.xml, site dirs exist --> <cores adminPath="/admin/cores"> <core name="site1" instanceDir="site1" /> <core name="site2" instanceDir="site2" /> </cores> <!-- from /etc/tomcat6/Catalina/localhost/solr.xml --> <Context docBase="/var/solr/solr.war" debug="0" privileged="true" allowLinking="true" crossContext="true"> <Environment name="solr/home" type="java.lang.String" value="/var/solr" override="true" /> </Context>

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  • Programming for Multi core Processors

    - by Chathuranga Chandrasekara
    As far as I know, the multi-core architecture in a processor does not effect the program. The actual instruction execution is handled in a lower layer. my question is, Given that you have a multicore environment, Can I use any programming practices to utilize the available resources more effectively? How should I change my code to gain more performance in multicore environments?

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  • Solr Multicore Admin Problem

    - by Daniel M
    Im trying to add a url based security constraint to solr deployed in websphere 6.1. If I specify the core name in the url of the constraint then the admin url for that core gives a 404. Has anyone had any success with this or any suggestions? Cheers

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  • Minimal "Task Queue" with stock Linux tools to leverage Multicore CPU

    - by Manuel
    What is the best/easiest way to build a minimal task queue system for Linux using bash and common tools? I have a file with 9'000 lines, each line has a bash command line, the commands are completely independent. command 1 > Logs/1.log command 2 > Logs/2.log command 3 > Logs/3.log ... My box has more than one core and I want to execute X tasks at the same time. I searched the web for a good way to do this. Apparently, a lot of people have this problem but nobody has a good solution so far. It would be nice if the solution had the following features: can interpret more than one command (e.g. command; command) can interpret stream redirects on the lines (e.g. ls > /tmp/ls.txt) only uses common Linux tools Bonus points if it works on other Unix-clones without too exotic requirements.

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  • SOLR multicore shared configuration

    - by Mark
    I'm using multiple cores in SOLR to enable offline population of indices (and then using SWAP to swap out the active core). I want to use the same solrconfig.xml file for both cores - can someone tell me where I should put this so it can be picked up by SOLR?

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  • Melhoria de Performance no .NET 4.5: Multicore Just-in-Time (JIT).

    - by anobre
    Olá pessoal! Dando uma lida nas melhorias de performance da plataforma .NET 4.5, me deparei com algo extremamente interessante: Multicore Just-in-Time (JIT). A teoria é muito simples: por que não utilizar vários núcleos para a compilação JIT? Além disto, será que seria possível compilar os métodos em uma determinada ordem, onde os primeiros fossem aqueles com maior probabilidade de execução? Isto parece meio loucura mas é o que o Multicore Just-in-Time (JIT) faz. E o melhor de tudo, de uma forma extremamente simples. As aplicações ASP.NET 4.5 já o fazem por default. Em outras ocasiões, basta executar duas linhas de código: uma indicando a pasta onde o arquivo que armazenará o profile ficará, e a outra para iniciar o procedimento. Este profile é o arquivo responsável por armazenar a ordem de compilação dos métodos, para que aqueles com maior chance de serem executados mais cedo sejam compilados antes. Código para este processo: ProfileOptimization.SetProfileRoot(@"C:\ProfileRoot"); ProfileOptimization.StartProfile("profile"); .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; } Esta otimização na compilação só será notada após a criação do profile. Portanto, na primeira vez nada será percebido. Ao final do processo, um arquivo com o nome escolhido (no caso profile) será criado, na pasta indicada como root: Fica a dica! Abraços!

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  • Java Parallel Programming

    - by user578524
    Dear All, I need to parallelize a CPU intensive Java application on my multicore desktop but I am not so comfortable with threads programming. I looked at Scala but this would imply learning a new language which is really time consuming. I also looked at Ateji PX Java parallel extensions which seem very easy to use but did not have a chance yet to evaluate it. Would anyone recommend it? Other suggestions welcome. Thanks in advance for your help Bill

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  • Will a database server perform better running on 2 CPUs with 16 cores or 4 CPUs with 8 cores?

    - by AlexOdin
    What I have: an online financial application (ASP.NET, C#) at peak we have 5K+ simultaneous users backend is running on Oracle 11g (active server + stand-by using Active Data Guard). At peak - 4K-5K database sessions Oracle is installed on Linux 5.8 (Oracle's unbreakable version) the database size: 7TB disk storage: NetApp (connected with 10GB network) I would like to replace old servers (IT will purchase HP blades BL685C). Servers will have 256GB of RAM. I need your help to figure out what to do with CPUs and cores. Options: 2 CPUs (2.3 GHz) with 16 cores each 4 CPUs (3.0 GHz) with 8 cores each Question: Which one should I pick? P.S. Next year, we will migrate from Oracle to SQL server. I hope, whatever option you recommend will work for both platforms

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  • NedMalloc / DlMalloc experiences

    - by Suma
    I am currently evaluating a few of scalable memory allocators, namely nedmalloc and ptmalloc (both built on top of dlmalloc), as a replacement for default malloc / new because of significant contention seen in multithreaded environment. Their published performance seems to be good, however I would like to check what are experiences of other people who have really used them. Were your performance goals satisfied? Did you experience any unexpected or hard to solve issues (like heap corruption)? If you have tried both ptmaalloc and nedmalloc, which of the two would you recommend? Why (ease of use, performance)?

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  • How are interrupts handled by dual processor machines?

    - by jeffD
    I have an idea of how interrupts are handled by a dual core CPU. I was wondering about how interrupt handling is implemented on a board with more than one physical processor. Is any of the interrupt responsibility determined by the physical board's configuration? Each processor must be able to handle some types of interrupts, like disk I/O. Unless there is some circuitry to manage and dispatch interrupts to the appropriate processor? My guess is that the scheme must be processor neutral, so that any processor and core can run the interrupt handler. If a core is waiting on a disk read, will that core be the one to run the interrupt handler when the disk is ready?

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  • Surprising results with .NET multi-theading algorithm

    - by Myles J
    Hi, I've recently wrote a C# console time tabling algorithm that is based on a combination of a genetic algorithm with a few brute force routines thrown in. The initial results were promising but I figured I could improve the performance by splitting the brute force routines up to run in parallel on multi processor architectures. To do this I used the well documented Producer/Consumer model (as documented in this fantastic article http://www.albahari.com/threading/part2.aspx#_ProducerConsumerQWaitHandle). I changed my code to create one thread per logical processor during the brute force routines. The performance gains on my work station were very pleasing. I am running Windows XP on the following hardware: Intel Core 2 Quad CPU 2.33 GHz 3.49 GB RAM Initial tests indicated average performance gains of approx 40% when using 4 threads. The next step was to deploy the new multi-threading version of the algorithm to our higher spec UAT server. Here is the spec of our UAT server: Windows 2003 Server R2 Enterprise x64 8 cpu (Quad-Core) AMD Opteron 2.70 GHz 255 GB RAM After running the first round of tests we were all extremely surprised to find that the algorithm actually runs slower on the high spec W2003 server than on my local XP work station! In fact the tests seem to indicate that it doesn't matter how many threads are generated (tests were ran with the app spawning between 2 to 32 threads). The algorithm always runs significantly slower on the UAT W2003 server? How could this be? Surely the app should run faster on a 8 cpu (Quad-Core) than my 2 Quad work station? Why are we seeing no performance gains with the multi-threading on the W2003 server whilst the XP workstation tests show gains of up to 40%? Any help or pointers would be appreciated. Regards Myles

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  • Do Scala and Erlang use green threads?

    - by CHAPa
    I've been reading a lot about how Scala and Erlang does lightweight threads and their concurrency model (actors). However, I have my doubts. Do Scala and Erlang use an approach similar to the old thread model used by Java (green threads) ? For example, suppose that there is a machine with 2 cores, so the Scala/Erlang environment will fork one thread per processor? The other threads will be scheduled by user-space (Scala VM / Erlang VM ) environment. Is this correct? Under the hood, how does this really work?

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