overhead

Why CUDA memory copy speed behaves like this, some constant driver overhead?

由 故事扮演 提交于 2019-12-13 15:13:23
问题 I always have a strange 0.04 ms overhead when working with memory in CUDA on my old GeForce 8800GT. I need to transfer ~1-2K to constant memory of my device, work with that data on it and get only one float value from the device. I have a typical code using GPU calculation: //allocate all the needed memory: pinned, device global for(int i = 0; i < 1000; i++) { //Do some heavy cpu logic (~0.005 ms long) cudaMemcpyToSymbolAsync(const_dev_mem, pinned_host_mem, mem_size, 0, cudaMemcpyHostToDevice

Calculating HashMap overhead in Java

由 隐身守侯 提交于 2019-12-10 15:49:33
问题 Let's say I'm storing 1000 objects in a hashmap. This hashmap is extended to allow me to map three dimensional coordinates to the objects stored in it; the objects inside have a fixed size. The hash key is a long integer. How would I go about figuring out (mathematically) the probable overhead for this structure? Is it significant enough that, for instance, if the data inside is around 256mb that the overhead will matter? Is there a reliable way (Aside from a profiler, which I've found are

In CUDA profiler nvvp, what does the “Shared/Global Memory Replay Overhead” mean? How is it computed?

由 不打扰是莪最后的温柔 提交于 2019-12-10 13:26:24
问题 When we use CUDA profiler nvvp , there are several "overhead"s correlated with instructions, for example: Branch Divergence Overhead; Shared/Global Memory Replay Overhead; and Local/Global Cache Replay Overhead. My Questions are: What cause(s) these overheads?And how are they computed? Similarly, how are Global Load/Store Efficiency computed? Attachment: I've found all the formulas computing these overheads in the 'CUDA Profiler Users Guide' packed in CUDA5 toolkit. 回答1: You can find some of

iOS: What is the processing overhead in invoking an Objective-C method?

由 北城以北 提交于 2019-12-10 07:36:11
问题 I am writing some real-time audio processing code, which is to be executed in an audio unit's render callback. This thread is at the highest priority level the system recognises. Apple instructs to minimise the amount of processing that goes on in this call. One of their recommendations is to avoid Objective-C method invocation. But why? What happens when an Objective-C method is invoked? what is the actual overhead? 回答1: Objective-C method resolution is dynamic. In other languages such as C

OpenMP drastic slowdown for specific thread number

由 倾然丶 夕夏残阳落幕 提交于 2019-12-09 11:53:05
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");

Java Proxy Discovering Bot

由 早过忘川 提交于 2019-12-08 00:44:19
问题 I have written a class, ProxyFinder which connects to random ips and first pings them, and if they respond, attempts to create a http proxy connection through common proxy ports. Currently, it is set up just connecting to random ips. This is relatively fast, discovering a few proxys an hour. However, I would like to somehow check if I have already previously connected to an ip. First I tried keeping them in a list, but that was using over 10GB of ram.. I included a method that I tried in the

Why is there overhead when calling functions?

由 五迷三道 提交于 2019-12-07 03:38:43
问题 Often, people speak of the calling of functions producing a certain amount of overhead , or an inescapable set of additional concerns and circumstances, in a program. Can this be better explained and compared to a similar program without the function call? 回答1: It depends on your compiler settings and the way it optimizes code. Some functions are inlined. Others are not. It usually depends on whether you're optimizing for size or for speed. Generally, calling function causes delay for two

Struct's contribution to type size

由 自闭症网瘾萝莉.ら 提交于 2019-12-05 22:00:38
问题 I am wondering why the following two types struct { double re[2]; }; and double re[2]; have the same size in C? Doesn't struct add a bit of size overhead? 回答1: No, it just merely composes all the elements into one higher-level element whose size is merely the individual elements' sizes added up (plus some padding depending on alignment rules, but that's out of the scope of this question). 回答2: Not if it can help it - no. C avoids overhead like the plague. And specifically, it avoids overhead

iOS: What is the processing overhead in invoking an Objective-C method?

由 守給你的承諾、 提交于 2019-12-05 12:23:40
I am writing some real-time audio processing code, which is to be executed in an audio unit's render callback. This thread is at the highest priority level the system recognises. Apple instructs to minimise the amount of processing that goes on in this call. One of their recommendations is to avoid Objective-C method invocation. But why? What happens when an Objective-C method is invoked? what is the actual overhead? Objective-C method resolution is dynamic. In other languages such as C or C++, a function call is set at compile time, essentially as a jump to the address that contains the

Why is there overhead when calling functions?

由 佐手、 提交于 2019-12-05 07:45:10
Often, people speak of the calling of functions producing a certain amount of overhead , or an inescapable set of additional concerns and circumstances, in a program. Can this be better explained and compared to a similar program without the function call? Francois Zard It depends on your compiler settings and the way it optimizes code. Some functions are inlined. Others are not. It usually depends on whether you're optimizing for size or for speed. Generally, calling function causes delay for two reasons: The program needs to hook to some random location in memory where your function code
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