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SubjectRe: many rx packets dropped since 2.6.37
From
2012/4/25 Eric Dumazet <eric.dumazet@gmail.com>:
> On Wed, 2012-04-25 at 16:38 +0200, Chris wrote:
>> 2012/4/25 Eric Dumazet <eric.dumazet@gmail.com>:
>> >> Why do we see dropped packets only in virtual environments and bonded
>> >> network interfaces and not on real network interfaces?
>> >
>> > This has to be investigated, eventually.
>>
>> Do you have the opportunity to test it? Just install fedora 16 (linux
>> 3.3) or ubuntu 12.04 (linux 3.2) as guest under kvm and use as virtual
>> network card virtio_net or e1000.
>>
>> You will see many lost rx packets and i have no idea why???
>
>
> You can use drop_monitor / dropwatch to figure out
>
> https://fedorahosted.org/dropwatch/
>
> http://prefetch.net/blog/index.php/2011/07/11/using-netstat-and-dropwatch-to-observe-packet-loss-on-linux-servers/

Hello Eric,

Okay this is a Fedora-16 VM under KVM with 4 minutes uptime only and dropwatch!

349 dropped packets in 4 minutes uptime??

[root@test ~]# uname -r
3.3.2-6.fc16.x86_64
[root@test ~]# dropwatch -l kas
Initalizing kallsyms db
dropwatch> start
Enabling monitoring...
Kernel monitoring activated.
Issue Ctrl-C to stop monitoring
1 drops at netlink_unicast+1bc
3 drops at ip_rcv_finish+f0
1 drops at __netif_receive_skb+583
1 drops at ip_rcv+d3
9 drops at ip_rcv_finish+f0
9 drops at ip_rcv_finish+f0
1 drops at __netif_receive_skb+583
6 drops at ip_rcv_finish+f0
1 drops at nf_hook_slow+12b
4 drops at ip_rcv_finish+f0
1 drops at __netif_receive_skb+583
4 drops at ip_rcv_finish+f0
1 drops at nf_hook_slow+12b
3 drops at ip_rcv_finish+f0
3 drops at nf_hook_slow+12b
2 drops at __netif_receive_skb+583
1 drops at ip6_mc_input+1f6
7 drops at ip_rcv_finish+f0
1 drops at ip_rcv_finish+f0
1 drops at netlink_unicast+1bc
1 drops at skb_queue_purge+20
2 drops at __netif_receive_skb+583
1 drops at ip_rcv_finish+f0
1 drops at nf_hook_slow+12b
1 drops at ip_rcv_finish+f0
1 drops at __netif_receive_skb+583
19 drops at ip_rcv+d3
2 drops at ip_rcv_finish+f0
37 drops at ip_rcv+d3
2 drops at __netif_receive_skb+583
43 drops at ip_rcv+d3
5 drops at ip_rcv_finish+f0
1 drops at __netif_receive_skb+583
1 drops at nf_hook_slow+12b
1 drops at ip6_mc_input+1f6
7 drops at ip_rcv_finish+f0
39 drops at ip_rcv+d3
2 drops at ip6_mc_input+1f6
1 drops at netlink_unicast+1bc
1 drops at skb_queue_purge+20
29 drops at ip_rcv+d3
7 drops at ip_rcv_finish+f0
2 drops at __netif_receive_skb+583
2 drops at ip6_mc_input+1f6
54 drops at ip_rcv+d3
3 drops at __netif_receive_skb+583
2 drops at nf_hook_slow+12b
3 drops at ip_rcv_finish+f0
1 drops at ip6_mc_input+1f6
36 drops at ip_rcv+d3
6 drops at ip_rcv_finish+f0
2 drops at __netif_receive_skb+583
1 drops at nf_hook_slow+12b
1 drops at icmpv6_rcv+305
37 drops at ip_rcv+d3
1 drops at __netif_receive_skb+583
2 drops at ip_rcv_finish+f0
4 drops at ip_rcv_finish+f0
39 drops at ip_rcv+d3
2 drops at __netif_receive_skb+583
1 drops at netlink_unicast+1bc
1 drops at skb_queue_purge+20
1 drops at nf_hook_slow+12b
38 drops at ip_rcv+d3
3 drops at __netif_receive_skb+583
2 drops at ip6_mc_input+1f6
1 drops at ip_rcv_finish+f0
46 drops at ip_rcv+d3
1 drops at __netif_receive_skb+583
1 drops at ip_rcv_finish+f0
^CGot a stop message
dropwatch> exit
Shutting down ...
[root@test ~]# ifconfig | grep dropped
RX packets:161562 errors:0 dropped:349 overruns:0 frame:0
TX packets:2140 errors:0 dropped:0 overruns:0 carrier:0
RX packets:4 errors:0 dropped:0 overruns:0 frame:0
TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
[root@test ~]# uptime
15:47:00 up 4 min, 3 users, load average: 0.01, 0.04, 0.03
[root@test ~]# netstat -s
Ip:
1553 total packets received
610 with invalid addresses
0 forwarded
0 incoming packets discarded
345 incoming packets delivered
478 requests sent out
71 dropped because of missing route
Icmp:
4 ICMP messages received
0 input ICMP message failed.
ICMP input histogram:
echo requests: 2
echo replies: 2
4 ICMP messages sent
0 ICMP messages failed
ICMP output histogram:
echo request: 2
echo replies: 2
IcmpMsg:
InType0: 2
InType8: 2
OutType0: 2
OutType8: 2
Tcp:
1 active connections openings
2 passive connection openings
0 failed connection attempts
0 connection resets received
2 connections established
2353 segments received
2096 segments send out
0 segments retransmited
0 bad segments received.
0 resets sent
Udp:
51 packets received
0 packets to unknown port received.
0 packet receive errors
51 packets sent
0 receive buffer errors
0 send buffer errors
UdpLite:
TcpExt:
1 TCP sockets finished time wait in fast timer
3 delayed acks sent
2 packets directly queued to recvmsg prequeue.
2 packets directly received from prequeue
2009 packets header predicted
165 acknowledgments not containing data received
IPReversePathFilter: 82
IpExt:
InMcastPkts: 13
InBcastPkts: 60
InOctets: 146431
OutOctets: 63310
InMcastOctets: 416
InBcastOctets: 12060
--
Chris


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