From mboxrd@z Thu Jan  1 00:00:00 1970
From: michi1@michaelblizek.twilightparadox.com (michi1 at michaelblizek.twilightparadox.com)
Date: Sun, 10 Feb 2013 13:29:32 +0100
Subject: MAX limit of file descriptor
In-Reply-To: <20130209051047.GA2806@debian.localdomain>
References: <20130209051047.GA2806@debian.localdomain>
Message-ID: <20130210122931.GA2269@grml>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

Hi!

On 13:10 Sat 09 Feb     , horseriver wrote:
> hi:)
> 
>    In one process ,what is the max number of opening file descriptor ?

Type "ulimit -a" in your shell. On my system (debian) the default is 1024.

>    Can it be set to infinite ?

Maybe, but at least it can be set very high.

>    In network programing ,what is the essential for  the maximum of connections 
>    dealed per second 

- Use non blocking i/o and epoll(). Do *not* create 1 process/thread for each
  connection and do not use use select(). 
- Obviously, the more memory your application uses, the more memory has to be
  put in the server. IIRC, 1 tcp connection uses ~1kb kernel memory.
- The same applies for cpu time. On the system side, you may want to recommend
  network adaptors which can be switched to polling instead of raising 1
  interrupt per packet. You should expect to see lots of small packets on the
  network.

	-Michi
-- 
programing a layer 3+4 network protocol for mesh networks
see http://michaelblizek.twilightparadox.com