hyperthreading

问题 I am trying to install HAXM for android studio but it is showing error: Now my system has VT-x enabled: after this I tried to disable HYPER-V but when i try through cmd it shows a error: In windows feature I dont have a HYPER-V option: I have uninstalled my AVAST anti virus and I have tried to disable HYPER-V through powershell also but it is not working.. I am using windows 8.1 64-bit OS with intel i5 Please Help Thanks in Advance!! 回答1: After Doing lot of search on internet about this

问题 Today I found a very strange problem. I ran Redhat Enterprise Linux 6, and the CPU was Intel E31275 (4 cores, 8 threads). I found one kernel thread (I called it as my_thread) didn't work correctly. With "ps" command, I found the status of my_thread was always running: ps ax 5545 ? R 3:14 [my_thread] 15774 ttyS0 Ss 0:00 -bash ... But its running time was always 3:14. Since it ws running, why didn't the total time increase? From the proc file /proc/5545/sched, I found the all statistics

问题 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 working perfectly... until I reached exactly 20, 22, and 24 threads. I kept breaking it down until I had this simple program #include <stdio.h> #include <omp.h> int main(int argc, char *argv[]) { int i, n, maxiter, threads, nsquared, execs = 0; double begin, end; if (argc != 4) { printf("4 args\n");

问题 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 proviso that both belong to the same process, i.e. in the same address space. Page 85 (2-55) - Intel® 64 and IA-32 Architectures Optimization Reference Manual : http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-optimization-manual.pdf 2.5.9 Hyper-Threading

问题 I use a simulation written in python/numpy/cython. Since i need to average over many simulation runs i use the multiprocessing module to run all the individual simulation runs in batches. At the office i have an i7-920 workstation with HT. At home i have an i5-560 without. I thought i could run twice as many instances of the simulation in each batch in the office and cut my running time in half. Surprisingly, the run time of each individual instance was doubled compared to the time it take on

问题 I am trying to find out how an OS (Windows, linux) assigns numbers to logical cpus in a Hyper threading enabled environment. ? Does both the OSs first serially assign numbers to the Physical CPUs and then start numbering the logical cpus or is there some other rule followed.. ? e.g. in 2 physical cpu system with hyper threading , does an OS assign number 0,2 to the first physical cpu and then 1,3 to second physical cpu .. ? Any references would be really appreciated. Thanks in advance.

问题 I know how to get the processor type, perhaps that's the only way, but I'm actually looking for a way to determine from an application whether it's running on a multi-core processor or on a hyper-threading single-core processor . (background: the hosting providers of some of my clients are very vague about what resources they make available through VMWare images. This application is supposed to run on multi-core, but has seen detrimental performance since its last "move". Normally, on multi

问题 I'm trying to determine the independent CPU's (specified with affinity ID's) for building ATLAS on a linux machine with 4 Intel CPU's with hyperthreading (ubuntu 12.04). The reason I'm doing this is that the ATLAS manual says to use only the physical cores on machines with hyper threading, on how to achieve this it says: "...you can tell ATLAS to use only the real cores if you learn a little about your machine. Unfortunately, ATLAS cannot presently autodetect these features, but if you

问题 Is there some sample code that exemplifies Intel's Hyperthreading performance? Is it at all accessible from user space, or does that CPU do all the work transparently for the programmer? This is for C, Linux. 回答1: Hyperthreading performance depends on many factors and is difficult to estimate. Just to shortly explain Hyperthreading: Each core has more then one register set, but no additional execution units The hyperthreads are scheduled more or less evenly So you only really get additional

问题 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 slow as 13.4s) at around 500% CPU when using the default #pragma omp parallel for , and the OpenMP speed up is only 2.5x at 5x CPU w/ g++-4.7 -O3 -fopenmp , on a 4-core 8-thread Xeon. I tried using schedule(static) num_threads(4) , and noticed that my programme always completes in 11.5s to 11.7s