Medialy wrote:
Problem solved. Thanks.
BTW, sometimes the program stops at function nfct_close() and never return!
I don't have an explanation for that, but it should not happen.
On Wed, Dec 30, 2009 at 8:10 PM, Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx
<mailto:pablo@xxxxxxxxxxxxx>> wrote:
Medialy wrote:
Hi,
I have written a program to log the nat behavior. the program works
well when traffic is low. But when the traffic reaches 1Gb, program
always error.
According to the previous discussions about this problem, I even set
the recv buffer size to 50MB and the error still exists.
Increasing the buffer size would not solve the problem, that will
only delay the ENOBUFS error. There are several reasons why you may
hit ENOBUFS:
a) your program is too slow to handle the Netlink messages that you
receive from the kernel at a given rate. This is easier to trigger
if the handling that you perform on every message takes too long.
b) the queue size is too small, but this does not seem to be your case.
ENOBUFS basically means that the kernel has to drop Netlink messages
because your user-space program cannot back-off.
Medialy:
Reason: system was overloaded due to the storage capability. The
program (2 threads) was set to use last CPU. When the traffic was
heavy, most of the computing power of last CPU was occupied by the
thread which wrote Netlink messages to the stroage.
Good analysis. It is a good idea to put the thread that digest the
Netlink message in a spare CPU. That reduces the chances to hit ENOBUFS.
I forgot to say but reducing the nice() value also help to avoid ENOBUFS.
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