Questions tagged [multicore]

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R studio one multi core CPU or dual single cores CPUS

So far I was using R on my home pc: i3 CPU, two cores, 4 threads. In order to run the code faster I was using the package 'DoSnow', utilizing 3 out of the 4 cores in order not to choke my system completely. However, now I got a server which has a two single core Xenons and I wonder: can I use the sa...
Mark2b
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Run music21 on full processor power

I am trying to create dataset by extracting only specific songs from larger dataset . By specific I mean songs only with two instruments where one is from keyboard family and another is from string family. Simplified code looks like this: for midi_file_path in Path(dir_path).glob('**/*.mid'): try:...
Konrāds Bušs
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OpenMP threads executing on same CPU core

Config : Windows 10, mingw-x64, Core 2 (4 logical) The following code #include #include #include int main() { #pragma omp parallel { std::printf ('Doing Stuff on thread: %d on Core #%d\n', omp_get_thread_num(),\ GetCurrentProcessorNumber()); } return 0; } Sometimes it gives output: Doing Stuff o...
Recoder
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Performance degrading when more threads/processes takes cores even when not all cores are used

To explore the CPU performance on Ubuntu, I'm using sysbench's cpu test. I'm also using taskset to bind certain CPUs to a process. The script I used to run the experiment is as below: for concur in {1..24} do end=$(($concur-1)) echo '--> Create $concur jobs' for i in $(seq 0 $end) do j=`expr $i \\*...
Michael Tong
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2

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How to run external program on multiple cpu cores using python?

I am trying to run multiple simulations on an external program, CalculiX, using python. I am aware that the python script can't run on multiple cpu cores but CalculiX is an external program which I am running through the os.system command. I need to run the simulations on multiple cores to save time...
Jacques Buys
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How to enable multicore processing with sklearn LDA?

I have a topics model using sklearn LDA. My corpus have ~75K documents and matrix shape generate from corpus is X.shape = (74645, 91542) When I pass this matrix to sklearn LDA it takes 3 hrs on my local and on server it is using 11 hrs. So my question is: Is there a way to use multicore processing i...
Nikhar Shah
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How to make H2O driverless AI use more cores on CPU?

My machine has 20 cores on its CPU, but when running Driverless AI, it uses only 4 of them.How can I make it use more cores for faster results?
Roshan Shah
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815

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Concurrent directory traversal algorithm hang problem

I have created a concurrent, recursive directory traversal and file processing program, which sometimes hangs after all parallel computations have finished but the 'primary' thread never continues with other tasks. The code is basically a fork-join style concurrent aggregator, and after the paralle...
akarnokd
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4

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What kind of apps can perform better on multi-core cpu?

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.
Mickey Shine
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MPI has only master nodes

I'm trying to use MPI with my 4 cores processor. I have followed this tutorial : http://debianclusters.org/index.php/MPICH:_Starting_a_Global_MPD_Ring But at the end, when I try the hello.out script, I get only server process (master nodes) : mpiexec -np 4 ./hello.out Hello MPI from the server proce...
Mibou
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foreach within package function: does not work on first call

I am trying to add parallel computation option to an R (netresponse) package based on doMC and multicore. The script works ok, but only on the second trial. To reproduce the bug, start R and run the script below. It gets stuck on the last line. After interrupting with ctrl-c I get a few messages of...
antagomir
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Manipulate Thread Implementation in JVM

Recently, I've been working on the deployment of concurrent objects onto multicore. In a sample, I use BlockingQueue.take() method whose specification mentions that it is blocking. It means that the method does not release the enclosing thread's resources such that it can be re-used for other concur...
nobeh
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Is ruby 1.9 capable of using multiple cores for indexing data in solr?

I have a ruby 1.9 rails 3.0.7 application that is using lucid/solr to index large amounts of text data (3GB or so). The data is stored in a MongoDB database and consists mainly of emails. One issue I'm having is that I'm trying to index the entire data initially when I establish the application so...
Dan L
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speeding up as.POSIXct on windows

I know that you can speed up the as.POSIXct function by using pvec, from the multicore package, but it only works on unix systems such as a mac. Is there a Windows equivalent, that would generate comparable speeds? Any benchmarking would be interesting to see...
h.l.m
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tbb::parallel_for running out of memory on machine with 80 cores

I am trying to use tbb::parallel_for on a machine with 160 parallel threads (8 Intel E7-8870) and 0.5 TBytes of memory. It is a current Ubuntu system with kernel 3.2.0-35-generic #55-Ubuntu SMP. TBB is from the package libtbb2 Version 4.0+r233-1 Even with a very simple task, I tend to run out of res...
Guido Kanschat
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Explanation of state replication of barrelfish

Can you tell how the Barrelfish OS is implementing the state replication of its kernel on each each core or closely-coupled 'shared' on cores in case e have a multi or many cores chip. As I am trying to understand this point, even I tried to check the source code, no more documentation explain this...
Abdel Hegazi
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Creating an R function to use mclapply from the multicore package

I need to analyze some simulated data with the following structure: h c x1 y1 x1c10 1 0 37.607056431 104.83097593 5 1 1 27.615251557 140.85532974 10 1 0 34.68915314 114.59312842 2 1 1 30.090387454 131.60485642 9 1 1 39.274429...
user1849779
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How to designate a Process/Thread to a certain core in a multi-core environment?

I mean, in the implementation of an OS, what mechanism can do this job? e.g., in the Linux kernel? Or, as we all know there are tools by which we can achieve this conveniently, like the Windows Task Manager, but what is the internal mechanism?
troore
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433

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Gwan - Why gwan determine only 1 core?

I am currently testing the gwan web server, I have a question about the default settings for the gwan worker, and the CPU Core detection. Running gwan on a Xen server (which contains a 4-core Xeon CPU), the gwan.log file reports that only got a single core was detected: './gwan -w 4' used to overrid...
moriya
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OpenMP different results 1 core vs multiple

I've been trying to make my program in C multicore the last few months, yet I keep getting this strange problem. Maybe some of you can help me out a little? The problem I'm having is that my program gives proper results when I let it calculate using only one thread. However, when I choose more threa...
user2257570
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CPU time on multicored/hyperthreaded

I need to observe the CPU time took by a process in a multicored/hyper-threaded. Suppose a Xeon, Opteron, etc. Let's assume I have 4 cores, hyper threaded, meaning 8 'virtual' cores. Let X the program I want to run an observed how much CPU time it took. If I run process X in my cpu, I get CPU time A...
hectorpal
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Regarding relationship between cores and ranks of a MPI program

As far as I know, in a multiprocessor environment any thread/process can be allocated to any core/processor so, what is meant by following line: the number of MPI ranks used on an Intel Xeon Phi coprocessor should be substantially fewer than the number of cores in no small part because of limited me...
Puneet S. Chauhan
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How is CPU time measured on Windows?

I am currently creating a program which identifies processes which are hung/out-of-control, and using an entire CPU core. The program then terminates them, so the CPU usage can be kept under control. However, I have run into a problem: When I execute the 'tasklist' command on Windows, it outputs thi...
Hammereditor2
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make multicore (-j) does not handle dependencies correctly?

I have a makefile with this line: parser_yacc.h parser_yacc.c : parser_yacc.y bison -y -d parser_yacc.y && mv y.tab.h parser_yacc.h && \ mv y.tab.c parser_yacc.c now I have several other lines that depend on parser_yacc.h. When I perform make everything runs fine. However when I run make -j4 I alw...
Chris Maes
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X10 code does not recognize the second core of the CPU

I wrote a canonical 'Hello, World' demo class in X10: class Hello { public static def main(args:Rail[String]):void { finish for (p in Place.places()) { at (p) async Console.OUT.println(here+' says hello'); } Console.OUT.println('Goodbye'); } } My computer has a 2-core CPU, but X10 code does not...
Alexei Odeychuk
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Is it possible to check maximum value of a variable in SPIN/PROMELA

In my model checking code, I'm only interested in finding the maximum value of a certain variable. The procedure I employ now is to have an assert statement assert( var < MAX_VALUE ), and keep changing the MAX_VALUE in a binary search fashion. However, it would be a lot better, if SPIN actually had...
MetallicPriest
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Parallelization of a loop which involves random sampling using mpi4py

I am new to parallelization and MPI. I am learning and experimenting with mpi4py. Currently I am trying to optimize the performance of a method which randomly samples for a desired point(satisfying a condition) in an interval. To give you a detailed idea, i created a sample program which is similar...
chaithu
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Is there a way to run SQLite queries from python asynchronously or in parrallel?

How can sqlite3 statements be run from python in some kind of 'non-sequential' way? Here is some code, basically straight from the python docs, on sqlite3. (I am assuming this code is executing sequentially): import sqlite3 conn = sqlite3.connect('::memory') c = conn.cursor() ###First sequence c.ex...
mgcdanny
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How to ensure that a thread is executed in another CORE?

Trying to execute a thread in another core, i use java.util.concurrent.executor I dont know if its enough to make the thread running in another core so, i want to know in witch core every thread is executed. Any idea? Executor executor = Executors.newSingleThreadExecutor(); executor.exec...
Nassim MOUALEK
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Running processes on different cores

I have some java classes(blackbox) which I call through jni from native C code. There are 4 parallel threads in my native code which need to be running always and they call some java classes occasionally, but these classes run really slow. I am of the opinion that threads run on a single core and us...
Alok Kumar
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How to stop all cores and run my code (in kernel space) on all the cores, in FreeBSD?

In FreeBSD kernel, how can I first stop all the cores, and then run my code (can be a kernel module) on all the cores? Also, when finished, I can let them restore contexts and continue executing. Linux has APIs like this, I believe FreeBSD also has a set of APIs to do this. edit: Most likely I did n...
WindChaser
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Do concurrency issues in kernel happen when using single core processor?

When a kernel is compiled on a multicore system, there will be multiple threads or processes operating simultaneously. So, concurrency problem will be an issue. However, when there is only one core in the processor. will it still be a problem?
Xin Li
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Control parallelism with BrightFutures, a “future” implementation in Swift

BrightFutures is a nice implementation of 'future' in the Swift language. https://github.com/Thomvis/BrightFutures I like to control the parallelism of multicore CPU with it. Does someone know a way to control the # of CPU cores/physical threads to be used?
kzhk
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Will python multiprocessing suffice for multi-CPU machines?

I am aware that you have to use something like MPI or python libraries like celery, jug, pp, etc, when you want to distribute processes over multiple machines, but is that necessary if you have a single machine with multiple CPU's? So if I had a machine whose motherboard has two or more CPU's (each...
user5915738
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Does System.nanotime leap back or forward

I found multiple (conflicting) sources on the internet about whether System.Nanotime does or does not 'leap back\forward' I found sources to indicate that clock resets do not affect System.nanotime. But do server restarts change system.nanotime? Are there situations in which System.Nanotime does le...
Ngm
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How to parallelize this structure?

I'm trying to parallelize the following structure using OpenMP in C++: x1,x2,y1,y2,k1,k2 = 0; a1,a2,b1,b2; //initialized to some value vec1,vec2; for (i=0;i
Finfa811
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Is VLFeat's SIFT implementation in parallel?

As we know, the downhill of SIFT compared to other detector/descriptors is speed: is usually much slower. However, parallel implementations could solve the problem even if we want to describe one image. Notice that I'm talking about using multiple cores, not GPU. VLFeat has its own SIFT implementati...
justHelloWorld
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Where is Linux Scheduler code about multicore?

I know currently Linux kernel is using CFS as the scheduler and I know the code is located in kernel/sched/fair.c. I checked the file 'fair.c' but I didn't find any part is assigning tasks to different cpu so I'm wondering is there part or other code that are working for load balancing or coordinat...
S.Wan
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php7 fail on windows multicore server

My application was getting error of $_GET variable don't exists on Windows 2008 R2 with 4 CPU cores. So I created this simple code to test.
Antonio Silva
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288

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Use Z3 in multicore server

I want to set up a system that will be fully dedicated to Z3. Let's say it has 4 cores and I would like to use all the power of the machine. I will be solving large formulas that have around 1000 incremental asserts. I would like to solve the formulas in a parallel fashion. I've read this question...
user1618465

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