Re: epoll,threading

[Ingo Oeser <ioe-lkml@rameria.de>]

Hi Arunachalam,

On Saturday 26 May 2007, Arunachalam wrote:
> I want to know in detail about , what the events (epoll or /dev/poll or
> select ) achieve in contrast to  thread per client.
> 
> i can have a thread per client and use send and recv system call directly
> right? Why do i go for these event mechanisms?

Try 30.000 clients or more on a x86 32bit box. 
That will show you the difference quite nicely :-)

More seriously: Thread per client scales only to a certain amount of clients
	per RAM. If you like to scale beyond that to like to minimize your state 
	per client. If you have a thread then you have a task structure as 
	unswappable memory in kernel, a per-thread stack, which is reducing 
	your virtual memory per process (you have only around 3GB of virtual 
	memory per process in Linux x86 32bit).

	So one uses a process or thread pool to scale beyond that. 
	Pool size is typically related to the amount of CPU cores in the system.

Regards

Ingo Oeser