The Web server decides how many people to support the simultaneous online factor

Often encounter some web users to do advisory server Support Online number of questions, here to do a brief introduction. Non-technical discussion, if there are omissions or errors, please forgive and guide.
In the case of a common single-channel server, the CPU handles multiple processes, not at the same time, (can be as precise as 1/1000 seconds), but serially. The CPU usually divides the time of 1 seconds into n parts, then processes the first process in the order of the 1th in 1 seconds, and processes the second process with the second one ... Using nth to process nth processes, that is, the CPU's processing power, is not how many applications are submitted within that second, but how many copies of the CPU time the system has.

For example, the system default number of processes can support 256, and the CPU will be 1 seconds divided into 100 parts, then the remaining 156 processes will be executed in the next second, the network card is requested to enter the memory queue, so usually memory is large, will feel support more people online, In essence, the CPU divides the time slice is related, the higher performance CPU divides the time slice possibly the more, namely the processing speed is fast.
Of course, a process here is not just a request, a process can usually contain 100 identical requests, so that the CPU in 1 seconds to process the number of requests for 100*100=10000, but we know that most users can not submit only one request in a minute, that is, just click on a link.

In addition, bandwidth is the most critical factor to support the number of people online, the server according to our guaranteed maximum bandwidth is 5M, that is, 5mbit/s, corresponding to the server, the maximum data transmission speed should be 5/8byte/s*1024=640k/s. A minute of traffic is about 640k/s*60=38400k, if each user occupies 10K per minute, that is, the number of people who support online access is 3840 persons within one minute. (The picture class and the video class site is not in this example, because the picture class video class each user absolutely exceeds 10K in a minute), however, we do not guarantee that each user only accesses one that station link in one minute, if each user points the station two link in one minute, then the support online number should be below 2000.
In conclusion, a low-end server usually supports up to 2000 people online, and is only suitable for ordinary Web servers and text-based forums. Does not include the picture class download class video class and so on. In fact, a server if the number of people online to achieve so much, it will need to add machines and bandwidth!

Excerpt from: http://support.chinaccnet.com/archives/6240.html

The Web server decides how many people to support the simultaneous online factor