cpu | 易学教程

How to measure cpu time and wall clock time?

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I saw many topics about this, even on stackoverflow, for example: How can I measure CPU time and wall clock time on both Linux/Windows? I want to measure both cpu and wall time. Although person who answered a question in topic I posted recommend using gettimeofday to measure a wall time, I read that its better to use instead clock_gettime . So, I wrote the code below (is it ok, is it really measure a wall time, not cpu time? Im asking, cause I found a webpage: http://nadeausoftware.com/articles/2012/03/c_c_tip_how_measure_cpu_time_benchmarking#clockgettme where it says that clock_gettime

Branch target prediction in conjunction with branch prediction?

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问题 EDIT: My confusion arises because surely by predicting which branch is taken, you are effectively doing the target prediction too?? This question is intrinsically linked to my first question on the topic: branch prediction vs branch target prediction Looking at the accepted answer: Unconditional branch, fixed target Infinite loop goto statement break or continue statement End of the 'then' clause of an if/else statement (to jump past the else clause) Non-virtual function call Unconditional

Why do we need to compile for different platforms (e.g. Windows/Linux)?

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I've learned the basics about CPUs/ASM/C and don't understand why we need to compile C code differently for different OS targets. What the compiler does is create Assembler code that then gets assembled to binary machine code. The ASM code of course is different per CPU architecture (e.g. ARM) as the instruction set architecture is different. But as Linux and Windows run on the same CPU, the machine operations like MOVE/ADD/... should be identical. While I do know that there are OS-specific functions like printing to a terminal, this functionality could be provided by different implementations

CPU and GPU differences

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问题 What is the difference between a single processing unit of CPU and single processing unit of GPU? Most places I've come along on the internet cover the high level differences between the two. I want to know what instructions can each perform and how fast are they and how are these processing units integrated in the compete architecture? It seems like a question with a long answer. So lots of links are fine. edit: In the CPU, the FPU runs real number operations. How fast are the same

move from pandas to dask to utilize all local cpu cores

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Recently I stumbled upon http://dask.pydata.org/en/latest/ As I have some pandas code which only runs on a single core I wonder how to make use of my other CPU cores. Would dask work well to use all (local) CPU cores? If yes how compatible is it to pandas? Could I use multiple CPUs with pandas? So far I read about releasing the GIL but that all seems rather complicated. Would dask work well to use all (local) CPU cores? Yes. how compatible is it to pandas? Pretty compatible. Not 100%. You can mix in Pandas and NumPy and even pure Python stuff with Dask if needed. Could I use multiple CPUs with

C++ code for CPU load and CPU temperature

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问题 I want to see CPU temperature and CPU load in Windows. I have to write it myself not using software like Core Temp. How can I access this information? I read a similar question to mine, but there was no useful answer:(. 回答1: Recently I have started a similar project. I needed to read the cpu temperature and to control the fan in Linux and Windows. I don't know much about C++ and VS and DDK but I figured how to write a simple kernel driver and a simple program with winring0. In my laptop (and

How do I cap my framerate at 60 fps in Java?

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问题 I am writting a simple game, and I want to cap my framerate at 60 fps without making the loop eat my cpu. How would I do this? 回答1: You can read the Game Loop Article. It's very important that you first understand the different methodologies for the game loop before trying to implement anything. 回答2: I took the Game Loop Article that @cherouvim posted, and I took the "Best" strategy and attempted to rewrite it for a java Runnable, seems to be working for me double interpolation = 0; final int

FLOPS Intel core and testing it with C (innerproduct)

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I have some misconceptions about measuring flops, on Intel architecture, is a FLOP one addition and one multiplication together? I read about this somewhere online and there is no debate that could reject this. I know that FLOP has a different meaning on different types of cpu. How do I calculate my theoretical peak FLOPS? I am using Intel(R) Core(TM)2 Duo CPU E7400 @ 2.80GHz. What exactly is the relationship between GHz and FLOPS? (even wikipedia's entry on FLOPS does NOT specify how to do this) I will be using the following methods to measure the actual performance of my computer (in terms

How to monitor resources during slurm job?

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I'm running jobs on our university cluster (regular user, no admin rights), which uses the SLURM scheduling system and I'm interested in plotting the CPU and memory usage over time, i.e while the job is running. I know about sacct and sstat and I was thinking to include these commands in my submission script, e.g. something in the line of #!/bin/bash #SBATCH <options> # Running the actual job in background srun my_program input.in output.out & # While loop that records resources JobStatus="$(sacct -j $SLURM_JOB_ID | awk 'FNR == 3 {print $6}')" FIRST=0 #sleep time in seconds STIME=15 while [ "

Portable way of detecting number of usable CPUs in Python

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问题 Per this question and answer -- Python multiprocessing.cpu_count() returns '1' on 4-core Nvidia Jetson TK1 -- the output of Python's multiprocessing.cpu_count() function on certain systems reflects the number of CPUs actively in use , as opposed to the number of CPUs actually usable by the calling Python program. A common Python idiom is to use the return-value of cpu_count() to initialize the number of processes in a Pool . However, on systems that use such a "dynamic CPU activation"