latency

问题 In the Img tag, we know that the image has an OnLoad event that fires when the images finish loading. But can we get the accurate measure when the image begin to download? I am trying to measure a website's Page Load Time, so knowing how long it takes for an image to load will be part of my analysis if that's possible. I would like to do it from an automated fashion, so I can measure real client experiences instead of putting my website on Yslow or PingDom( http://tools.pingdom.com/fpt/). I

问题 I write web based applications. Performance is obviously a key factor. Whilst database load and page rendering time are things I have control of, the users internet connection is not. What I'm looking for is a way to indicate what sort of a connection a user has. Something along the lines of a traffic light in the corner of a website that shows the user what sort of a connection they have to the site and therefore indicating what sort of perceived performance they should expect. e.g. Maybe

问题 I am experimenting with connecting my Galaxy Ace to my laptop via WiFi. Both devices are connected to a router via WiFi, and both sides use Java. After a TCP connection gave me very high pings from time to time, I decided to base the connection on UDP, to be able to control when the packets are actually sent. However, it seems like Android still buffers UDP packets and does not send them immediately. This, or it shuts down WiFi completely, if there is no outgoing data transmitted for some

问题 I have a link between a host and a switch. The link has a bandwidth & a latency. How to calculate the time of 2 packets(with size 1KB) to be transferred from Host A to Switch 1 ? Here's the diagram(I am talking about the first link) Note: I just want to calculate it manually for these values, I want to know the principles/laws of calculating these problems. 回答1: Propagation time = (Frame Serialization Time) + (Link Media Delay) + (Queueing Delay) + (Node Processing Delay - if known) Formulas:

问题 The code below shows my attempt to run an algorithm on single GPUs and feed data to it using a FIFO queue. The data exists in a CSV file. I use a separate python thread to read from the file one line at a time and enqueue the line into a FIFO. N = 16 num_ckfs =80000 q = [0.01 for i in range(N)] q_ckfs = np.array([q for i in range(num_ckfs)]) r = [5] r_ckfs = np.array([r for i in range(num_ckfs)]) init_var = [10.0 for i in range(N)] init_var_ckfs = np.array([init_var for i in range(num_ckfs)])

问题 I am working on a little online multiplayer pong game with C# and XNA. I use sockets to transfer data between two computers on my personnal LAN. It works fine. The issue is with speed : the transfer is slow. When I ping the second computer, it shows a latency of 2 ms. I set up a little timer inside my code, and it shows a latency of about 200 ms. Even when the server and the client are on the same computer (using 127.0.0.1), the latency still about 15 ms. I consider this as slow. Here are

问题 I am currently programming a simple application that takes input from a midi device and outputs the corresponding sound. I have gotten everything to work now, but there is two problems: First of all, when i plug in a midi device AFTER the program has started or disconnect it while the program is running, it will not get recognized. Second of all, the latency is very high on OSX, Linux (Raspbian) and Windows alike. Does anyone know the solution to either of these issues? Here is what i have so

问题 for a client a run a website on Windows Azure (Websites). I run in reserved mode and have two medium insances. I run these PHP sites on Windows and I have a separate MySQL server (running on Windows). Memory enough, no high utilization, but once every minute or two minutes I have an explained higher latency (3 seconds, instead of 300 milliseconds). Does one experience the same behaviour, or recognize this? All happens within one Windows Azure datacenter. When I loadtest it with a tool, the

问题 I am working with streaming RTSP using LibVLC. I have it working where I can view the stream, but the latency is set to the default ~2seconds. On the Ubuntu Desktop I can launch vlc with the following options to improve the latency greatly: $ vlc -vvv rtsp://192.168.2.1:1234 --network-caching=50 --clock-jitter=0 --clock-synchro=0 however, when I add these options to LibVLC, there is no positive effect: ArrayList<String> options = new ArrayList<>(); options.add("-vvv"); options.add("--network

问题 I'm using RN42 (http://www.microchip.com/wwwproducts/en/RN42) bluetooth module at 115200 bauds (UART SSP mode) to send very small (1 - 20 byte) serial data messages between a computer and a ATMega328 MCU. I find that the latency for one message is somewhere around 60 - 100 ms. I would need 10 ms or less in my application. I'm wondering if this is even possible with bluetooth 2.1 devices.´ I know that theoretically bluetooth packets can be sent every 2 * 625 us from one end since 625 us is the