[ovs-discuss] Tweaking FlowStats

Ajeeth Kannan (RIT Student) ak5378 at rit.edu
Fri Dec 9 08:32:38 UTC 2016


Hello,

I have been trying to learn how flowstats is being implemented in
openvswitch. So, I have tweaked flowstats by adding a field named
*check_field *in the datapath module. check_field would be incremented same
as the packet_count. Accordingly, I have tracked the netlink connection
between the userspace request and kernel-space reply in the code. To verify
my changes, I have tried *ovs-dpctl dumpflows * and *ovs-ofctl-dumpflows. *I
have given the logs for both commands below.

 *ovs-dpctl dumpflows*

recirc_id(0),in_port(2),eth(src=3e:0a:67:88:be:50,dst=3a:
26:f3:7a:d8:1b),eth_type(0x0800),ipv4(src=10.0.0.1,dst=10.0.0.2,frag=no),
*packets:19*, bytes:1862, *check_field:19*, used:0.329s, actions:1
recirc_id(0),in_port(1),eth(src=3a:26:f3:7a:d8:1b,dst=3e:
0a:67:88:be:50),eth_type(0x0800),ipv4(src=10.0.0.2,dst=10.0.0.1,frag=no),
*packets:19*, bytes:1862, *check_field:19,* used:0.330s, actions:2

 *ovs-ofctl-dumpflows*

ofp_print_flow_stats_reply in print.cNXST_FLOW reply (xid=0x4):
 cookie=0x20000010000000, duration=7.410s, table=0, *n_packets=1*,
n_bytes=42, *check_field=7935465029190709108*, idle_timeout=5, idle_age=2,
priority=1,arp,in_port=2,dl_src=3a:26:f3:7a:d8:1b,dl_dst=3e:0a:67:88:be:50
actions=output:1
 cookie=0x20000013000000, duration=2.393s, table=0, *n_packets=0*,
n_bytes=0, *check_field=7162168704237371450*, idle_timeout=5, idle_age=2,
priority=1,arp,in_port=1,dl_src=3e:0a:67:88:be:50,dl_dst=3a:26:f3:7a:d8:1b
actions=output:2
 cookie=0x20000011000000, duration=7.405s, table=0, *n_packets=7*,
n_bytes=686, *check_field=18446744073709486336*, idle_timeout=5,
idle_age=0, priority=1,ip,in_port=1,dl_src=3e:0a:67:88:be:50,dl_dst=
3a:26:f3:7a:d8:1b,nw_src=10.0.0.1,nw_dst=10.0.0.2 actions=output:2
 cookie=0x20000012000000, duration=7.403s, table=0, *n_packets=7*,
n_bytes=686, *check_field=576461851848605696*, idle_timeout=5, idle_age=0,
priority=1,ip,in_port=2,dl_src=3a:26:f3:7a:d8:1b,dl_dst=
3e:0a:67:88:be:50,nw_src=10.0.0.2,nw_dst=10.0.0.1 actions=output:1
 cookie=0x0, duration=9.577s, table=0,* n_packets=17*, n_bytes=1290,
*check_field=143271862657351680*, idle_age=0, priority=0
actions=CONTROLLER:65535

I am able to get the check_field value as expected in ove-dpctl. But, Why
am I getting garbage values in ovs-dpctl ?

Thank you,
Ajeeth Kannan
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