On Sun, Feb 10, 2013 at 8:29 PM, <michi1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Hi!
Type "ulimit -a" in your shell. On my system (debian) the default is 1024.
On 13:10 Sat 09 Feb , horseriver wrote:
> hi:)
>
> In one process ,what is the max number of opening file descriptor ?
Hi Michael, nice to see u again.
BTW, many of the parameters as reported by ulimit, also has to be taken with some doubts:
ulimit -a
core file size (blocks, -c) unlimited
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 47543
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 47543
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
the above is for Ubuntu 12.04 with 32-bit kernel (3.2.0) but of course we know that max file size has a limit - depending on whether it is ext2 or ext3 or ext4. cannot remember the exact nos, but general conceptual level, there is a limit.
even for "CPU time"...it is limited by the underlying bit length of representation for time. as usual...i don't know the details :-(, just concept. sorry :-(.
Maybe, but at least it can be set very high.
> Can it be set to infinite ?
- Use non blocking i/o and epoll(). Do *not* create 1 process/thread for each
> In network programing ,what is the essential for the maximum of connections
> dealed per second
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
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Regards,
Peter Teoh
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