Imagine I want to have one main thread and a helper thread run as the two hyperthreads on the same physical core (probably by forcing their affinity to approximately ensure this). The main thread ...

I'm curious what the CPU ordering is in Linux. Say I bind a thread to cpu0 and another to cpu1 on a hyperthreaded system, are they both going to be on the same physical core. Given a Core i7 920 wi...

This question has an answer that says: Hyper-threading duplicates internal resources to reduce context switch time. Resources can be: Registers, arithmetic unit, cache. Why did CPU designers ...

In Is OpenMP (parallel for) in g++ 4.7 not very efficient? 2.5x at 5x CPU, I determined that the performance of my programme varies between 11s and 13s (mostly always above 12s, and sometimes as sl...

I have a multithreaded program running on a quad-core Intel i7. When I execute Runtime.getRuntime.availableProcessors(), I get 8, and I know that hyperthreading is available on this CPU. However, ...

I'm using an OpenMP code on a HyperThreaded CPU. If all else were equal, how would performance change on a non-HyperThreaded CPU? I notice a 100% processor utilization, no matter how many threads...

I have Intel i7-2600K quadcore, with hyperthreading enabled on Ubuntu 12.04. I know that I can find out how many cores I have in Python with import multiprocessing; multiprocessing.cpu_count(), but...

Does a hyperthreading CPU implement parallelism or just concurrency (context switching)? My guess is no parallelism, only concurrency by context switching.

Hyper-Threading Technology is a form of simultaneous multithreading technology introduced by Intel. These resources include the execution engine, caches, and system bus interface; the sharing of r...

Given: An entirely CPU bound very large (i.e., more than a few CPU cycles) job, and A CPU with four physical and a total of 8 logical cores, should 8, 16, and 28 threads perform better than 4? I ...

I have some questions hanging in the air without an answer for a few days now. The questions arose because I have an OpenMP and an OpenCL implementations of the same problem. The OpenCL runs perfec...

On my machine, windows 7 - Enterprise with 1 x Intel Xeon E5-1660 0 @ 3.30Ghz (6 cores/cpu with Hyper Threading activated), Environment.ProcessorCount return 12 which is exact. On a Windows Server...

I've read several Questions and articles regarding how to decide on a size for a thread pool. Questions include: How to choose thread pool size? What is the relationship between number of CPU cor...

I'm a researcher in statistical pattern recognition, and I often run simulations that run for many days. I'm running Ubuntu 12.04 with Linux 3.2.0-24-generic, which, as I understand, supports multi...

We have recently purchased a dual Intel X5650 workstation to run a floating-point intensive simulation, under Ubuntu 10.04. Each X5650 has 6 cores, so there are 12 cores in total. The code is triv...

Does the Hyper Threading allow to use of L1-cache to exchange the data between the two threads, which are executed simultaneously on a single physical core, but in two virtual cores? With the prov...

I'm trying to gather system information and noticed the following on an Intel Xeon E5420: After executing CPUID(EAX=1), EDX[28] is set, indicating Hyper-threading support, despite the fact that th...

I am developing large dense matrix multiplication code. When I profile the code it sometimes gets about 75% of the peak flops of my four core system and other times gets about 36%. The efficiency d...

Background I have an EP (Embarassingly Parallell) C application running four threads on my laptop which contains an intel i5 M 480 running at 2.67GHz. This CPU has two hyperthreaded cores. The fo...

Does anyone know of a way to query the number of physical cores from MATLAB? I would specifically like to get the number of physical rather than logical cores (which can differ when hyperthreading ...

I ran an OpenMP program to perform the Jacobi method, and it was working very well, 2 threads performed slightly over 2x 1 thread, and 4 threads 2x faster than 1 thread. I felt everything was worki...

I was reading a review of the new Intel Atom 330, where they noted that Task Manager shows 4 cores - two physical cores, plus two more simulated by Hyperthreading. Suppose you have a program with ...

If you're spawning multiple threads (or processes) concurrently, is it better to spawn as many as the number of physical processors or the number of logical processors, assuming the task is CPU-bou...

My computer has a quadcore i7 processor. I'm studying parallelization of scientific simulations. How does hyperthreading impact on parallel performances? I know I should never use more than 4 worki...

I'm making an Android game and the performance difference between single core phones such as Galaxy S and dual-core Galaxy S2 is comparable to night and day. Thus instead of making different versio...