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What is more efficient? Using pow to square or just multiply it with itself?
...n if a single operation (like computing the square of some value) takes up 10% of the application's execution time (which IME is quite rare), and even if optimizing it saves 50% of the time necessary for that operation (which IME is even much, much rarer), you still made the application take only 5%...
由12306.cn谈谈网站性能技术 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...相当的复杂。不信，你可以问问所有传统和电务零售业的企业，看看他们管理库存是多么难的一件事。不然，就不会有那么多人在问凡客的库存问题了。（你还可以看看《乔布斯传》，你就知道为什么Tim会接任Apple的CEO了，最主...
Change navbar color in Twitter Bootstrap
...vbar-default-brand-hover-color: darken(@navbar-default-link-color, 10%);
@navbar-default-brand-hover-bg: transparent;
// Navbar toggle
@navbar-default-toggle-hover-bg: #ddd;
@navbar-default-toggle-icon-bar-bg: #ccc;
@navbar-default-toggle-border-color: #ddd...
Skip List vs. Binary Search Tree
... in the case of low contention that they tested (70% lookups, 20% inserts, 10% deletes); they actually beat the lock-free solution for this scenario when they made their skip list big enough, i.e. going from 200K to 2M elements, so that the probability of contention on any lock became negligible. It...
Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing?
...oportions between children of a Component (for example, child 1 should use 10% of space, child 2 40%, child 3 50%), is it possible to achieve that without implementing a custom LayoutManager?
Any of the Big-Three can, can't even GridBag (never bothered to really master, too much trouble for too li...
What does 'COLLATE SQL_Latin1_General_CP1_CI_AS' do?
...eral things that it does. Why do you assume that the OP only wants to know 10% of the answer? If all of the info is presented, each person can decide how much of it to take. But if only some info is given, then the choice was made for them. I choose to provide as much info as possible because most o...
What is the fastest integer division supporting division by zero no matter what the result is?
...5000 iterations you hit your d==0 case. While 50% might not happen often, 10% or 1% could easily happen, or even 90% or 99%. The test as displayed only really tests "if you basically never, ever go down a branch, does branch prediction make removing the branch pointless?", to which the answer is "y...
LR性能测试结果样例分析 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...这个指标在很多系统中都提及到，比如电信的、金融的、企业资源管理的等等。举个例子，我们楼下的建行，假如每天的业务类别是这样的：20个开户，5个销户，300个存款，500取款，100个汇款等，那么在做他们的营业系统测试时...
Is std::vector so much slower than plain arrays?
...ge Pixel to:
struct Pixel
{
unsigned char r, g, b;
};
Result: about 10% faster. Still slower than an array. Hm.
# ./vector
UseArray completed in 3.239 seconds
UseVector completed in 5.567 seconds
Idea #4 - Use iterator instead of loop index
How about using a vector<Pixel>::iterator...
Why does my application spend 24% of its life doing a null check?
... slower for remote memory, NUMA accesses slow down your memory accesses by 10%. In addition, if you only have free memory on a single NUMA node, all the processes needing memory on the starved node will be allocated memory from the other node which accesses are more expensive. Even worst, the oper...