low-latency

问题 Looking at Jeff Dean's famous latency guides Latency Comparison Numbers (~2012) ---------------------------------- L1 cache reference 0.5 ns Branch mispredict 5 ns L2 cache reference 7 ns 14x L1 cache Mutex lock/unlock 25 ns Main memory reference 100 ns 20x L2 cache, 200x L1 cache Compress 1K bytes with Zippy 3,000 ns 3 us Send 1K bytes over 1 Gbps network 10,000 ns 10 us Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD Read 1 MB sequentially from memory 250,000 ns 250 us Round trip

来源： https://stackoverflow.com/questions/64392845/when-busy-spining-java-thread-is-bound-to-physical-core-can-context-switch-happ

问题 OBJECTIVE: I'm building a FPV robot, I want to control it with a with a webbrowser over a local wi-fi connection. I'm using a raspberry pi 3B+ with Raspbian Stretch. I built my own motor control and power regulator hat. After lots of research testing, I decided to use node.JS as http server and socket.io to provide a low latency bidirectional communication with my robot. This stack achieve about 7ms of latency. Picture of the robot PROBLEM: I need to stream low latency video from an USB

问题 OK first and foremost, performance is most important here so I doubt a map would work. I have a list of structs (about 16 of them) like struct A { ... }; struct B { ... }; ... each are different and each are of different sizes. I'm wondering what elegant way we might be able to do something along the lines of: char BufferA[sizeof(struct A)]; char BufferB[sizeof(struct B)]; then write some method or mapping to return BufferA if you are working with struct A. Speed is definitely the most

问题 I wrote the server that accepts connection and bombards messages ( ~100 bytes ) using text protocol and my implementation is able to send about loopback 400K/sec messages with the 3rt party client. I picked Netty for this task, SUSE 11 RealTime, JRockit RTS. But when I started developing my own client based on Netty I faced drastic throughput reduction ( down from 400K to 1.3K msg/sec ). The code of the client is pretty straightforward. Could you, please, give an advice or show examples how

问题 I'd like to know what the differences are between the ZeroMQ and WebSockets protocols . I know WebSockets was designed for web browser clients, but I'm assuming it can also be used server to server. And, in that case, I'm wondering if it would be good to use WebSockets instead of something else like ZeroMQ for real-time messaging . Specifically, I'm worried about reliability and missing messages in case of temporary network failure. 回答1: A: Real-Time-Messaging is a nice tag, however You may

问题 When conjoining socket.io/node.js and redis pub/sub in an attempt to create a real-time web broadcast system driven by server events that can handle multiple transports, there seems to be three approaches: 'createClient' a redis connection and subscribe to channel(s). On socket.io client connection, join the client into a socket.io room. In the redis.on("message", ...) event, call io.sockets.in(room).emit("event", data) to distribute to all clients in the relevant room. Like How to reuse

问题 When conjoining socket.io/node.js and redis pub/sub in an attempt to create a real-time web broadcast system driven by server events that can handle multiple transports, there seems to be three approaches: 'createClient' a redis connection and subscribe to channel(s). On socket.io client connection, join the client into a socket.io room. In the redis.on("message", ...) event, call io.sockets.in(room).emit("event", data) to distribute to all clients in the relevant room. Like How to reuse

问题 I'm doing some research on In-Memory databases and am wondering what type of applications would benefit the most from the predictable latency characteristic of In-Memory databases. I can imagine online gaming, such as first person shooter games. I'm just wondering what other type of applications. 回答1: Not much surprisingly the very applications, that benefit from predictable latency (be it low, or not -- latency jitter bothers...) low-latency edge : HPC , where nanoseconds and sub-nanosecond

问题 I'm considering developing an app for the upcoming Windows 8. The app requires low-latency audio recording and playback, and I'm trying find out whether the OS will support that (as opposed to other platforms). So what I'd like to know is: Is there a low-latency audio API in Windows 8? Will it be supported on platforms other than PC (e.g. tablets)? Thanks! 回答1: WASAPI was introduced with Windows Vista as the low-latency audio API. It is available both to desktop and to Metro style