SEARCH KEYWORD -- Memory allocation
Buffcacher
What should a ‘cache’ be? It means a lot of things, but to my mind the default programming type should be: “keep around expensive-to-generate bits of read-only data in case we need them again, or until the computer really needs that RAM for something else†I was writing a custom video editing program in Python (interesting choice of language for that problem) and I wanted to cache decoded frames; but I just wasn’t happy with the memory management of explici...
Buffer,Cache,Web browser,Memory,RAM 2012-02-24 05:10:10
Qualities of a great business presentation
When it comes to business, every day in the industry is spent trying to convince someone into buying your brand, your product or services, no doubt you will find yourself making a lot of pitches and presentations for new products, partners and stakeholders among other things. Having great presentation skills is essential to running a successful business and getting as many people believing in your brand as possible. Great presentations have the following qualities Killer slides PowerPoint slides...
Tips for improving PHP efficiency
0. Using single quote to replace double quote to enclose string literal, this will be a bit faster. Because PHP engine will search variables in double quoted string. 1. If a method in class can be declared as static, then make it static, this will be 4 times faster. 2. $row["id"] is 7 times faster than $row[id] 3. echo is faster than print, and you should use multiple parameters instead of string concatenation, i.e use comma(,) instead of dot(.) to concatenate string. For example echo $str1,$str...
PHP, efficiency, tips 2012-10-01 19:39:06
What will the value of Integer.valueOf(127) == Integer.valueOf(127) be in Java?
Do you really understand how Java does the integer comparison? OK, ignore the statements in the post title. What we are interested in is another set of comparison statements. Let's first see below code snippet. public class IntegerComparison { public static void main(String[] args) { Integer a = 127, b = 127; Integer c = 128, d = 128; System.out.println(a == b); System.out.println(c == d); } } What do you think the output will be? Are they both displaying true? You will find out t...
About tmpfs
tmpfs is another confusing name in Linux kernel, its implementation is in mm/shmem.c, shmem has no relation to tmpfs at first glance although we know tmpfs is based on memory. We can understand why we use this name by seeing where this is used. In a desktop Linux system, tmpfs is loaded usually: % grep tmpfs /proc/mountsdevtmpfs /dev devtmpfs rw,seclabel,nosuid,relatime,size=1958956k,nr_inodes=489739,mode=755 0 0tmpfs /dev/shm tmpfs rw,seclabel,nosuid,nodev,relatime 0 0tmpfs /run tmpfs rw,seclab...
tmpfs,Linux,file system 2013-06-14 12:10:56
Smuggling data in pointers
While reading up on The ABA Problem I came across a fantastic hack. The ABA problem, in a nutshell, results from the inability to atomically access both a pointer and a "marked" bit at the same time (read the wikipedia page). One fun, but very hackish solution is to "smuggle" data in a pointer. Example:#include "stdio.h"void * smuggle(void * ptr, int value){ return (void *)( (long long)ptr | (value & 3) );}int recoverData(void * ptr){ return (long long)ptr &...
An ex-Mozilla employee's view about Chrome
Chrome now becomes the most popular web browser on the planet because it provides excellent user experience. As a general user, we think it's fast and easy to use. How about those who develop web browsers? How do they think about Chrome? Abhinav Sharma ,an ex-Mozilla employee and now Facebook employee, shared his opinion about Chrome. Mozilla fights an uphill battle given Google's advertising budget and capacity to have some incredibly good engineers and designers work on Chrome. They also came ...
Some thoughts about competitive programming
Many programmers may have experience in participating different kinds of coding competition while they are in college. Many of them are hired by top IT companies for their excellent performance during these kinds of coding competitions. There are some famous competitions organized by IT companies such as Google Code Jam, Facebook hackathons etc. Coding competitions are places where programmers can show their talents in programming and the skills they have. Usually programmers will solve some to...
Coding,competition 2014-03-02 07:26:21
The tips of learning Linux kernel
As the Linux kernel has become one of the most gigantic and complex software project in the world, its complication scare many novices away. In this post, I will give some personal experience on how to learn Linux kernel, and hope these tips can offer some help to newcomers. (1) Download vanilla kernel and install it. Yes, I suggest you can find a physical machine, or if you really don’t have one at hand, virtual machine is also OK. Download the newest vanilla k...
Data as code
What is a good command line parser API? A good command line parser should consider below 5 aspects: Support convenient help information generation Support sub commands, for example, git has push,pull,commit sub commands. Support single character option, word option, flag option and option with parameter. Support default option, for example, if no -port is set, set it as 5037 Support usage model, for example, tar's -c and -x is mutually exclusive, they belong to different usage models. Here are...
Command line,API 2013-08-08 22:40:36
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