tcpdump mailing list archives

Re: HUGE packet-drop


From: "M. V." <bored_to_death85 () yahoo com>
Date: Wed, 26 Jan 2011 05:32:37 -0800 (PST)

hi,
thank you all for your answers, sorry that for the delay on my reply, i wasn't 
at work on Tuesday.

i tested your suggestions but got no luck at all.

from your posts, i got 4 different approaches to my problem:

1) i reset kernel parameters as what Gabe suggested, but i got no changes in 
results.

2) i tried to set different parameters with ethtool -G option, i could just set 
"rx" parameters up to 1020, and this didn't solve anything for me:
#  ethtool -G eth0 rx 1020
# ethtool -g eth0
Ring parameters for eth0:
Pre-set maximums:
RX:        1020
RX Mini:    0
RX Jumbo:    4080
TX:        255
Current hardware settings:
RX:        1020
RX Mini:    0
RX Jumbo:    0
TX:        255

3) i got the a modified version of libpcap-0.9.8 (Phil Wood version) which 
apparently uses MMAP, and recompiled tcpdump with it, but the results didn't get 
better.
# PCAP_FRAMES=max PCAP_VERBOSE=1 PCAP_TO_MS=0 PCAP_STATS=0x1fff tcpdump -i eth0 
-w /cache/netdata.pcap -s 0

4) i tried to perform what Gabe told about running tcpdump on the same core, 
with something like this:
# cat /proc/interrupts | grep eth0
1268: XXXXXX XXXXXX XXXXXX XXXXX 
# echo "1" > /proc/irq/1268/smp_affinity
#taskset -p 0x1 tcpdump -i eth0 -w /cache/dump.pcap -s 0 (i also tried "taskset 
-p 0x5" , because i wasn't sure which of them i had to set) but the results were 
the same.


so, i dont know what else to do, seems like nothing works for me :-S
1) does anyone have any other suggestions that may help?
2) about MMAP support in Debian kernel: i installed Debian5.0.3 from original 
ISO file. does anyone know if MMAP exists in its kernel by default? how can i 
get sure about that?
3) my server (HP Proliant DL360 G5) has 2 onboard ethernet cards, "Broadcom 
NetXtreme II" (and i also tried a different PCI-Express card). has anyone 
experienced any similar problem with Broadcom NICs?

thank you.



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