multicore

Forcing multiple threads to use multiple CPUs when they are available

由 给你一囗甜甜゛ 提交于 2019-11-26 23:29:41
I'm writing a Java program which uses a lot of CPU because of the nature of what it does. However, lots of it can run in parallel, and I have made my program multi-threaded. When I run it, it only seems to use one CPU until it needs more then it uses another CPU - is there anything I can do in Java to force different threads to run on different cores/CPUs? When I run it, it only seems to use one CPU until it needs more then it uses another CPU - is there anything I can do in Java to force different threads to run on different cores/CPUs? I interpret this part of your question as meaning that

Why doesn't the Go statement execute in parallel?

由 牧云@^-^@ 提交于 2019-11-26 23:04:28
问题 I'm testing this Go code on my VirtualBoxed Ubuntu 11.4 package main import ("fmt";"time";"big") var c chan *big.Int func sum( start,stop,step int64) { bigStop := big.NewInt(stop) bigStep := big.NewInt(step) bigSum := big.NewInt(0) for i := big.NewInt(start);i.Cmp(bigStop)<0 ;i.Add(i,bigStep){ bigSum.Add(bigSum,i) } c<-bigSum } func main() { s := big.NewInt( 0 ) n := time.Nanoseconds() step := int64(4) c = make( chan *big.Int , int(step)) stop := int64(100000000) for j:=int64(0);j<step;j++{

different behavior when using different number of multicoring workers

由 一个人想着一个人 提交于 2019-11-26 21:17:28
问题 I am playing around a bit with my program (trying to multicore a few parts) and I've noticed the "CPU history" looks a bit different, depend on how many workers I start. 2-4 workers seems to produce a "stable" workflow, however pegging 5-8 workers produces erratic behavior (from zero to max, see pictures). I should point out that all runs started out with "smooth" max capacity (e.g. 2 cores with only 25%), and started to exhibit erratic behavior only after a minute or so. What's going on? I

How do I turn on multi-CPU/Core C++ compiles in the Visual Studio IDE (2008)?

由 [亡魂溺海] 提交于 2019-11-26 20:11:38
问题 I have a Visual Studio 2008 C++ project that has support for using multiple CPUs/cores when compiling. In the VCPROJ file I see this: <Tool Name="VCCLCompilerTool" AdditionalOptions="/MP" ... I can't find where that was turned added via the IDE and I want to set up another project that uses all of my cores during compilation. I found tons of references to the MSDN /MP page but that is for using the command line; I have yet to find any references to setting that with the IDE. How do I do that?

multi core processing in for loop using numpy

由 六月ゝ 毕业季﹏ 提交于 2019-11-26 17:48:44
问题 I calculated vector using numpy. How can I calculate vector using multicore and numpy? import numpy as np num_row, num_col = 6000, 13572 ss = np.ones((num_row, num_col), dtype=np.complex128) ph = np.random.standard_normal(num_row) fre = np.random.standard_normal(num_row) tau = np.random.standard_normal(num_col) for idx in range(num_row): ss[idx, :] *= np.exp(1j*(ph[idx] + fre[idx]*tau)) 回答1: We could leverage broadcasting to have a NumPy based solution - ss = np.exp(1j*(ph[:,None] + fre[:

Does pthread_mutex_lock contains memory fence instruction? [duplicate]

由 独自空忆成欢 提交于 2019-11-26 16:28:43
问题 This question already has answers here : Does guarding a variable with a pthread mutex guarantee it's also not cached? (3 answers) Closed 6 days ago . Do pthread_mutex_lock and pthread_mutex_unlock functions call memory fence/barrier instructions? Or do the the lower level instructions like compare_and_swap implicity have memory barriers? 回答1: Please take a look at section 4.11 of the POSIX specification. Applications shall ensure that access to any memory location by more than one thread of

How do you make good use of multicore CPUs in your PHP/MySQL applications?

由 喜夏-厌秋 提交于 2019-11-26 15:19:40
问题 I maintain a custom built CMS-like application. Whenever a document is submitted, several tasks are performed that can be roughly grouped into the following categories: MySQL queries. HTML content parsing. Search index updating. Category 1 includes updates to various MySQL tables relating to a document's content. Category 2 includes parsing of HTML content stored in MySQL LONGTEXT fields to perform some automatic anchor tag transformations. I suspect that a great deal of computation time is

What is some example code for demonstrating multicore speedup in Python on Windows?

由 梦想的初衷 提交于 2019-11-26 14:33:35
问题 I'm using Python 3 on Windows and trying to construct a toy example, demonstrating how using multiple CPU cores can speed up computation. The toy example is rendering of the Mandelbrot fractal. So far: I have avoided threading, since the Global Interpreter Lock prohibits multicores in this context I'm ditching example code that won't work on Windows because it lacks the forking capability of Linux Trying to use the "multiprocessing" package. I declare p=Pool(8) (8 is my number of cores) and

Compiling with g++ using multiple cores

由 蹲街弑〆低调 提交于 2019-11-26 12:34:29
问题 Quick question: what is the compiler flag to allow g++ to spawn multiple instances of itself in order to compile large projects quicker (for example 4 source files at a time for a multi-core CPU)? 回答1: You can do this with make - with gnu make it is the -j flag (this will also help on a uniprocessor machine). For example if you want 4 parallel jobs from make: make -j 4 You can also run gcc in a pipe with gcc -pipe This will pipeline the compile stages, which will also help keep the cores busy

Does python support multiprocessor/multicore programming?

由 强颜欢笑 提交于 2019-11-26 12:01:44
What is the difference between multiprocessor programming and multicore programming? preferably show examples in python how to write a small program for multiprogramming & multicore programming Glyph There is no such thing as "multiprocessor" or "multicore" programming. The distinction between "multiprocessor" and "multicore" computers is probably not relevant to you as an application programmer; it has to do with subtleties of how the cores share access to memory. In order to take advantage of a multicore (or multiprocessor) computer, you need a program written in such a way that it can be
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