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Questions tagged [multiprocessor]

71 questions
32
votes
4 answers

Gradle android build for different processor architectures

I want to build 4 separate apks for 4 different Android CPU processor architectures (armeabi armeabi-v7a x86 mips) using Gradle. I have native OpenCV libraries built for 4 CPU architectures in the libs folder. libs -armeabi -armeabi-v7a …
Blukee
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18
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5 answers

What happens if two process in different processors try to acquire the lock at EXACTLY same time

Ok, so I am reading about synchronization, and I read through various algorithms such as spinlocks, semaphores, and mutex to avoid race condition. However, these algorithms can't prevent race condition in SMP when multiple proceses access the data…
SHH
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15
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5 answers

Stop reading process output in Python without hang?

I have a Python program for Linux almost looks like this one : import os import time process = os.popen("top").readlines() time.sleep(1) os.popen("killall top") print process the program hangs in this line : process =…
Barakat
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14
votes
6 answers

"Work stealing" vs. "Work shrugging"?

Why is it that I can find lots of information on "work stealing" and nothing on "work shrugging" as a dynamic load-balancing strategy? By "work-shrugging" I mean pushing surplus work away from busy processors onto less loaded neighbours, rather than…
John
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11
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2 answers

How locks are implemented on multiple cores

For a uni-processor, the lock algorithm is pretty simple. Lock(threadID) { Disable Interrupts If lock is already owned by same thread{ Restore Interrupts return } if lock is free { make lock busy set current thread as the…
user447851
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11
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4 answers

How do threaded systems cope with shared data being being cached by different cpus?

I'm coming largely from a c++ background, but I think this question applies to threading in any language. Here's the scenario: We have two threads (ThreadA and ThreadB), and a value x in shared memory Assume that access to x is appropriately…
csj
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9
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3 answers

Force C# application to use a single core in a PC with a multicore processor

I am using the Haptek People Putty player for my C# application and I've seen people say in the forums that it doesn't work well with a multicore processor. My application runs well on my Core 2 Duo laptop but it lags a lot when I try running it on…
Paul
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8
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2 answers

Best Practice for Stopwatch in multi processors machine?

I found a good question for measuring function performance, and the answers recommend to use Stopwatch as follows Stopwatch sw = new Stopwatch(); sw.Start(); //DoWork sw.Stop(); //take sw.Elapsed But is this valid if you are running under multi…
Ahmed
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8
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7 answers

Parallel coding Vs Multithreading (on single cpu)

can we use interchangeably "Parallel coding" and "Multithreading coding " on single cpu? i am not much experience in both, but i want to shift my coding style to any one of the above. As i found now a days many single thred application are…
K. Santosh
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6
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4 answers

What can I do to make my C# application take advantage of multiple processor cores?

I've been doing some tests about the way a .NET C# application uses resources, like CPU or memory. I wrote some loops that calculate values for a large amount of numbers and I'm satisfied with the weight of the algorithm. I have a Quad Core 2.4 GHz…
Rosmarine Popcorn
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6
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3 answers

How can I modify my perl script to use multiple processors?

Hi I have a simple script that takes a file and runs another Perl script on it. The script does this to every picture file in the current folder. This is running on a machine with 2 quad core Xeon processors, 16gb of ram, running RedHat Linux.…
Alos
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5
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1 answer

How do I find the cpu the current thread is running on, for Mac and BSD?

I'm looking for a function on Mac OS and BSD that's equivalent to Linux's sched_getcpu(), and Windows' GetCurrentProcessorNumberEx() in order to implement a library for cpu-local storage. It's clearly possible to emulate this with the cpuid or…
Jeffrey Yasskin
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4
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2 answers

Determining the number of available cores on a machine?

I want my software to create one thread per core, obviously different Macs have a different number of cores. Does anyone know how to (programmatically, via Cocoa) determine the number of cores?
Geesu
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4
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1 answer

multiprocessing not achieving full CPU usage on dual-processor windows machine

I am working on a dual-processor windows machine and am trying to run several independent python processes using the multiprocessing library. Of course, I am aiming to maximize the use of both CPU's in order to speed up computation time. The details…
Severin
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3
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2 answers

How does Nvidia's Fermi GPU issue threadblocks to streaming multiprocessor

Assume I have 8 threadblocks and my GPU has 8 SMs. Then how does GPU issue this threadblocks to the SMs? I found some programs or articles suggest a breadth-first manner, that is , each SM runs a threadblock in this example. However, according to a…
Antony Yu
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