I just setup a Extra Large Heavy Computation EC2 instance to throw it at my Genetic Algorithms problem, hoping to speed up things. This instance has 8 Intel Xeon processors (around 2.4Ghz each) and 7 Gigs of RAM. On my machine I have an Intel Core Duo, and matlab is able to work with my two cores just fine by runinng: matlabpool open ...
Hi, I was wondering if it would be possible to run app not at 100% of the cpu but at a specific amount of the cpus. I see different usage of this , we can better balance concurrent application ( we may want to have balance app 50% to have fair apps/agent/... ) i was also wondering if the power consumption would not be better if t...
Hi, I have a program that starts up and creates an in-memory data model and then creates a (command-line-specified) number of threads to run several string checking algorithms against an input set and that data model. The work is divided amongst the threads along the input set of strings, and then each thread iterates the same in-memor...
Hi, I developed time ago a open mpi code. Now I am working on it again and would like to do some testing. For reasons I can not avoid I can only use now a single core computer (my pc) for programming and testing. I know there are virtual machines. In the same fashion I wonder if I could get a virtual machine with a eight cores cpu, so ...
What would be the fastest portable bi-directional communication mechanism for inter-process communication where threads from one application need to communicate to multiple threads in another application on the same computer, and the communicating threads can be on different physical CPUs). I assume that it would involve a shared memory...
Hi guys, I'm posting this question to ask for advice on how to optimize the use of multiple processors from R on a Windows XP machine. At the moment I'm creating 4 scripts (each script with e.g. for (i in 1:100) and (i in 101:200), etc) which I run in 4 different R sessions at the same time. This seems to use all the available cpu. I ...
I have spend all morning trying to set up multiple cores on a SOLR installation that runs under Apache Tomcat server without success. My solr.xml looks like this: <solr persistent="false" sharedLib="lib"> <cores adminPath="/admin/cores"> <core name="core0" instanceDir="/multicore/core0"> <property name="dataDir" value="...
Hi I'm learning Haskell and I'd like to write some multithreaded programs now to see the performance gains from that in a functional language. I can find some references to it on the internet but never a proper introduction to it. Can anyone point me to a guide which is understandable for someone who knows the syntax fairly well, but is ...
I've read a lot on this topic already both here (e.g., stackoverflow.com/questions/1713554/threads-processes-vs-multithreading-multi-core-multiprocessor-how-they-are or http://stackoverflow.com/questions/680684/multi-cpu-multi-core-and-hyper-thread) and elsewhere (e.g., ixbtlabs.com/articles2/cpu/rmmt-l2-cache.html or software.intel.com/...
I just want to know that if there is a simple way of judging what kind of apps can perform better on multi-core cpu? Such as Memcached, redis, MySQL, Cassandra and so on. ...
Hi everyone. I will try my best to explain my problem and my line of thought on how I think I can solve it. I use this code for root, dirs, files in os.walk(downloaddir): for infile in files: f = open(os.path.join(root,infile),'rb') filehash = hashlib.md5() while True: data = f.read(10240) if len(data) =...
This sample code compares serial method with threaded method, on Quad core processor. The code just uses GetPixel() to read all pixels from 4 images. I found that the speed up is around 65%, why it does not equal 75% as I have 4 cores and all of them are fully utilized? P.S: Can you check the code as I do not do any I/O, and no other p...
I have a big solution with more than 40 projects. Almost half of them are test projects. In my project we use both Code Contracts, Code Analysis, Style Analysis. I want to be able to build the projects that are not dependent in parallel on my quad core CPU. How can I setup msbuild to build the projects in parallel? ...
The attached simple Java code should load all available cpu core when starting it with the right parameters. So for instance, you start it with java VMTest 8 int 0 and it will start 8 threads that do nothing else than looping and adding 2 to an integer. Something that runs in registers and not even allocates new memory. The prob...
Hello, I am totally a novice in Multi-Core Programming, but I do know how to program C++. Now, I am looking around for Multi-Core Programming library. I just want to give it a try, just for fun, and right now, I found 3 APIs, but I am not sure which one should I stick with. Right now, I see Boost's MPI, OpenMP and TBB. For anyone who h...
If more than one core on a processor is accessing the same memory address, will they thrash each other's caches or will some snooping protocol allow each to keep the data in L1-cache? I am interested in a general answer as well as answers for specific processors. How many layers of cache are invalidated? Will accessing another address w...
I have read many of the good questions and answers around multi-core programming how-tos etc. I am familiar with concurrency, IPC, MPI etc but what I need is advice on how to measure speed-up which will help in making a business case of spending the time to write such code. Please don't answer with "well run it with single-core code then...
If I have X cores on my machine and I start X threads. Let's assume for the sake of argument that each thread is completely separated in terms of the memory, hdd, etc it uses. Is the OS going to know to send each thread to a core or do more time slicing on one core for multiple threads. What the question boils down to, is if I have X co...
Is memcached capable of making full use of multi-core? Or is there any way tuning this? ...
I've got some multi threaded code that typically runs great, but every so often it will break. I'm trying to pinpoint the problem, but using OpenMP is making that more difficult (the problem does not occur in serial). I know that multiple access to a variable (race conditions) often crashes a program. I've got a list shared between the ...