Bugtraq mailing list archives
Re: UDP packet handling weird behaviour of various operating systems
From: aland () striker ottawa on ca
Date: Fri, 27 Jul 2001 10:53:25 -0400
Michal Zalewski <lcamtuf () gis net> wrote:
Try the same via loopback device - should not work. I believe this is not Linux kernel UDP handling problem. It might be, as suggested, but something between hardware and software, instead (like "IRQ congestion"), and probably should work for everything - TCP, ICMP?
At the last Linux Kernel Summit, Jamal Hadi Salim had a proposal for speeding up packet handling in the 2.5 kernel. The issue is currently that each packet coming into a network interface triggers an interrupt. It's the interrupt servicing overhead that is slowing the machine. The proposal for 2.5 was to disable interrupts on an interface after the first packet, and use other methods for noticing and grabbing the later packets. There are other operating systems (QNX, etc) that do this already. Jamal's tests showed that removing this overhead drastically sped up the network response, and removed much of the CPU overhead.
Of course I can be wrong - all I say is that I was not able to reproduce this behavior in my test network, maybe because it is 10 Mbit,
Implementations which appear to work under small loads may not scale to higher loads. Alan DeKok.
Current thread:
- UDP packet handling weird behaviour of various operating systems Stefan Laudat (Jul 25)
- Re: UDP packet handling weird behaviour of various operating systems Michal Zalewski (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Kevin Day (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Cade Cairns (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Michal Zalewski (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Cade Cairns (Jul 27)
- Re: UDP packet handling weird behaviour of various operating systems aland (Jul 27)
- Re: UDP packet handling weird behaviour of various operating systems Stefan Laudat (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Michal Zalewski (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Stefan Laudat (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Niels Bakker (Jul 27)
- RE: UDP packet handling weird behaviour of various operating systems David LeBlanc (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Radu-Adrian Feurdean (Jul 27)
- Re: UDP packet handling weird behaviour of various operating systems Michal Zalewski (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems trop (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Paul Sack (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Stefan Laudat (Jul 26)
- Re: UDP packet handling weird behaviour of various operating systems Sean Hunter (Jul 27)
- Re: UDP packet handling weird behaviour of various operating systems Stefan Laudat (Jul 26)