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  Hello, Kernel!

When we learn module programming, the first small program must be hello, kernel!. For a novice, how do we avoid some mistakes and how to fix the bugs we have when writing the first module program? Is there any example we can refer to? Here is one example. 1. Write the hello.c 01 #include <linux/init.h> 02 #include <linux/module.h> 03 #include <linux/kernel.h> 04 //Compulsory 05 //Module lincese declaration 06 MODULE_LICENSE("GPL"); ...

   module,kernel,Linux     2013-05-03 03:33:52

  gethostbyname vs getaddrinfo

getaddrinfo is slower than ping when resolving domain names. I think ping uses gethostbyname to resolve a domain name. The question becomes whether getaddrinfo is slower than gethostbyname. After testing with both functions, we find that getaddrinfo is really slow compared to gethostbyname. By strace tracking,  we find getaddrinfo will communicate with DNS server 10 times and gethostbyname will communicate with DNS server communication twice.gethostbyname is an old way to resolve domain nam...

   C++,network,DNS     2012-08-15 14:06:34

  Why does LinkedIn migrate to NodeJS from Ruby?

Node.js, the server-side JavaScript-based software platform used to build scalable network applications, has been all the rage among many developers for the past couple of years. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices. Because of these advantages, there are many websites are migrating to Node.js.One of them is LinkedIn. LinkedIn was initially built on Ruby...

   LinkedIn,NodeJS,Ruby     2014-03-21 23:39:25

  System programming is still there

System programming is the practice of writing system software. System software lives at a low level, interfacing directly with the kernel and core system libraries. Your shell and your text editor, your compiler and your debugger, your core utilities and system daemons are all system software. But so are the network server, the web server, and the database. These components are entirely system software, primarily if not exclusively interfacing with the kernel and the C library. But nowadays more...

   System programming     2014-02-27 05:46:48

  Convert HTML to DOM elements using JavaScript

In some cases, one would want to convert a HTML string to the DOM elements so that JavaScript can handle them easily. This is frequently used when one get some data from third party APIs where the data is in HTML format. In JavaScript, there are a couple of ways one can use to convert HTML to DOM elements. DOMParser document.createElement DOMParser DOMParser can parse XML or HTML source stored in a string into a DOM Document. After the conversion, the normal JavaScript call of h...

   JAVASCRIPT,DOMPARSER,DOCUMENT.CREATEELEMENT,HTML,DOM     2017-08-18 22:51:46

  How to optimize MySQL insert statement

For a big data system, one problem is the data access efficiency, one more problem is that the data insertion is very slow. We had a service system, the data loading process would take 4-5 hours. This time consuming operation is risky since if the program is interrupted during the loading process, it might be rerun, this will be troublesome. So it's necessary to improve the insertion efficiency for big data systems. Here we provide two optimization suggestions. 1. Combine multiple insert stateme...

   MySQL,insert,optimization     2012-10-24 22:03:13

  Three things you should never put in your database

As I've said in a few talks, the best way to improve your systems is by first not doing "dumb things". I don't mean you or your development staff is "dumb", it's easy to overlook the implications of these types of decisions and not realize how bad they are for maintainability let alone scaling. As a consultant I see this stuff all of the time and I have yet to ever see it work out well for anyone. Images, files, and binary data Your database supports BLOBs so it must be a good idea to shove ...

   Database,BLOB,Log,Image     2012-05-02 04:44:25

  SSH Security and You - /bin/false is *not* security

Backstory While at RIT around 2004 or 2005, I discovered that a few important machines at the datacenter allowed all students, faculty, and staff to authenticate against them via ssh. Everyone's shells appear to be set to /bin/false (or some derivative) on said machines, so the only thing you'll see after you authenticate is the login banner and your connection will close. I thought to myself, "Fine, no shell for me. I wonder if port forwarding works?" ...

   Linux,Security,/bin/false,SSH     2012-02-06 07:46:29

  Cache them if you can

“The fastest HTTP request is the one not made.” I always smile when I hear a web performance speaker say this. I forget who said it first, but I’ve heard it numerous times at conferences and meetups over the past few years. It’s true! Caching is critical for making web pages faster. I’ve written extensively about caching: Call to improve browser caching(lack of) Caching for iPhone Home Screen AppsRedirect caching deep diveMobile cache file sizesImproving app ...

   Cache,HTTP request,Websiite     2012-03-27 12:54:02

  Why Building a Mobile App is Hard

Kent Nguyen has a great article about how building iOS apps takes a lot of work. And, here at Parse, we agree. Making a well-designed app is not a trivial task. Many non-developers hugely underestimate the amount of sweat and tears that goes into a single app. The big component that is overlooked and that Kent stresses is the server component. An app is not an island. Users expect their apps to richly interact with the internet. This means you need to worry about developing code on servers, com...

   Mobile app,Hard,Chanllenges,Platform     2012-02-01 04:45:45