what are the values for /proc/sys/net/core/rmem_max and
/proc/sys/net/core/rmem_default? (are these things you have set in sysctl.conf?)
doing a google search for tcpdump packets dropped by kernel is also suggesting
increasing the size of the tcpdump buffer
add -B 8102 to your command line (default is 2k)
there was also a note on this page that disabling hyperthreading ended up
helping a lot (I've heard hyperthreading as being between a +10% and -50%
performance change, depending on your workload)
http://serverfault.com/questions/421789/lots-of-dropped-packages-when-tcpdumping-on-busy-interface
David Lang
On Tue, 1 Oct 2013, Robert wrote:
Date: Tue, 01 Oct 2013 16:03:31 -0400
From: Robert <[email protected]>
Reply-To: rsyslog-users <[email protected]>
To: rsyslog-users <[email protected]>
Subject: Re: [rsyslog] Tr : Re: perfomance tweaking
[rcortiz@simon ~]$ sudo nice -10 /usr/sbin/tcpdump -i eth2.10 -s 90 -nn port
514 | cut -c 1-8 | uniq -c
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth2.10, link-type EN10MB (Ethernet), capture size 90 bytes
47731 16:02:09
67135 16:02:10
81738 16:02:11
82093 16:02:12
92387 16:02:13
92027 16:02:14
160009 16:02:15
238179 16:02:16
238225 16:02:17
238241 16:02:18
237878 16:02:19
237898 16:02:20
237947 16:02:21
237904 16:02:22
237959 16:02:23
237977 16:02:24
238275 16:02:25
238042 16:02:26
238188 16:02:27
238102 16:02:28
236230 16:02:29
238234 16:02:30
237905 16:02:31
238273 16:02:32
238219 16:02:33
238520 16:02:34
238340 16:02:35
238211 16:02:36
238473 16:02:37
^C6014858 packets captured
7310296 packets received by filter
1280878 packets dropped by kernel
Robert
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