ping performance issues 2.6 v 2.4

Hi


Below was originally posted to alt.comp.os.linux - I've since realised
this is probably the more approriate NG:

I'm having some issues with some new linux 2.6 servers I've set up
(Centos 4.2). Windows XP clients are having issues establishing TCP
connections to them (for email etc), and I'm checking all the normal
things such as firewalls, cabling, duplex settings, tcpdumps etc.


What's strange is that these Windows client work fine on the 2.4 kernel

servers which are being retired.


Anyway, in the course of my investigations, I've noticed that a ping
flood on localhost takes much less time on my 2.4x servers than on my
2.6x ones (1 second v 144 seconds):


2.4 example:


[r...@2.4box root]# ping -V
ping utility, iputils-ss020124


[r...@2.4box root]# ping -f -c 10000 localhost
PING localhost.localdomain (127.0.0.1) from 127.0.0.1 : 56(84) bytes of

data.


--- localhost.localdomain ping statistics ---
10000 packets transmitted, 10000 received, 0% loss, time 900ms
rtt min/avg/max/mdev = 0.011/0.011/0.048/0.004 ms, ipg/ewma 0.090/0.012

ms


2.6 example:


[r...@2.6box ~]# ping -V
ping utility, iputils-ss020927


[r...@2.6box ~]# ping -f -c 10000 localhost
PING localhost.localdomain (127.0.0.1) 56(84) bytes of data.


--- localhost.localdomain ping statistics ---
10000 packets transmitted, 10000 received, 0% packet loss, time
141440ms
rtt min/avg/max/mdev = 0.014/0.017/0.043/0.004 ms, pipe 2, ipg/ewma
14.145/0.018 ms


There also seems to be quite a marked different when done accross a
real interface over the network.


Now I'm not too worried about this - as long as someone can verify this

is normal and they see the same thing. Then I can move on the other
causes of my main problem.


Cheers


Tim