>"Jun Wang" <junwan...@cestc.cn> writes:
>
>>>Mike Pattrick <m...@redhat.com> writes:
>>>
>>>> On Tue, Mar 4, 2025 at 10:51 AM Aaron Conole <acon...@redhat.com> wrote:
>>>>>
>>>>> Jun Wang via discuss <ovs-discuss@openvswitch.org> writes:
>>>>>
>>>>> >> Hello,
>>>>> >
>>>>> >> Yes, this will result in better ovs-tcpdump performance. The reason
>>>>> >> why it hasn't been added so far is because we can't guarantee or even
>>>>> >> check for the existence of any given DPDK driver at runtime in a
>>>>> >> generic fashion.
>>>>> >>
>>>>> >> One option would be to select this type of interface with a
>>>>> >> non-default command line flag.
>>>>> >
>>>>> > Hi, I also believe that choosing a non-default command line flag
>>>>> > to support this is a good option, allowing customers to decide
>>>>> > whether or not
>>>>> > to use this flag.
>>>>> > However, there are still some details to consider, such as whether to
>>>>> > allow users to configure the virtio-user port queue,
>>>>> > and whether virtio-user usage requires affinity configuration, etc.
>>>>>
>>>>> ovs-tcpdump will already support using `--mirror-to` as a destination.
>>>>> Wouldn't that be an appropriate flag? There's a lot involved with setup
>>>>> for a successful DPDK environment, and as you note lots of user required
>>>>> input.
>>>>
>>>> Unfortunately, mirror-to only lets you set the interface name. It will
>>>> still try to create a tap device and add it to OVS. If the interface
>>>> already exists, ovs-tcpdump will quit with an error.
>>>
>>>Hrrm... I thought it shouldn't:
>>>
>>> if sys.platform in _make_taps and \
>>> mirror_interface not in interfaces():
>>> _make_taps[sys.platform](mirror_interface,
>>> ovsdb.interface_mtu(interface))
>>> tap_created = True
>>> else:
>>> tap_created = False
>>>
>>>But I guess interfaces() might not match because the DPDK devices won't
>>>appear in /dev/net (or likely be dumped from netifaces function).
>>>
>>>Maybe the fix there could be to make mirror-to aware of these other
>>>devices (for instance, maybe searching the interfaces in OVSDB).
>>
>> Yes, I have actually tried using mirror-to, and it does result in an error.
>>
>> The error message and the corresponding code are as follows:
>>
>> [root@compute0-dpdk /]# ovs-tcpdump -i vh-userclient-e5281ddf-c8 --mirror-to
>> veth1
>>
>> ERROR: Mirror port (veth1) exists for port vh-userclient-e5281ddf-c8.
>>
>> if ovsdb.port_exists(mirror_interface):
>>
>> print("ERROR: Mirror port (%s) exists for port %s." %
>>
>> (mirror_interface, interface))
>>
>> sys.exit(1)
>
>Probably need a bit of rework around the use case - can you try the
>following (I didn't really test it well, just trying to see if the idea
>is good)
>
>---
>diff --git a/utilities/ovs-tcpdump.in b/utilities/ovs-tcpdump.in
>index 187eafdf25..2070678b3a 100755
>--- a/utilities/ovs-tcpdump.in
>+++ b/utilities/ovs-tcpdump.in
>@@ -421,13 +421,16 @@ def py_which(executable):
> for path in os.environ["PATH"].split(os.pathsep))
>-def teardown(db_sock, interface, mirror_interface, tap_created):
>+def teardown(db_sock, interface, mirror_interface, tap_created,
>+ created_mirror):
> def cleanup_mirror():
> try:
> ovsdb = OVSDB(db_sock)
> ovsdb.destroy_mirror(interface, ovsdb.port_bridge(interface))
>- ovsdb.destroy_port(mirror_interface, ovsdb.port_bridge(interface))
>- if tap_created is True:
>+ if created_mirror:
>+ ovsdb.destroy_port(mirror_interface,
>+ ovsdb.port_bridge(interface))
>+ if tap_created:
> _del_taps[sys.platform](mirror_interface)
> except Exception:
> print("Unable to tear down the ports and mirrors.")
>@@ -505,15 +508,21 @@ def main():
> if sys.platform in _make_mirror_name:
> mirror_interface = _make_mirror_name[sys.platform](interface)
>+ created_mirror = True
> if sys.platform in _make_taps and \
>- mirror_interface not in interfaces():
>+ mirror_interface not in interfaces() and \
>+ not ovsdb.port_exists(mirror_interface):
> _make_taps[sys.platform](mirror_interface,
> ovsdb.interface_mtu(interface))
> tap_created = True
> else:
>+ if mirror_interface in interfaces() or \
>+ ovsdb.port_exists(mirror_interface):
>+ created_mirror = False
> tap_created = False
>- if mirror_interface not in interfaces():
>+ if mirror_interface not in interfaces() and \
>+ not ovsdb.port_exists(mirror_interface):
> print("ERROR: Please create an interface called `%s`" %
> mirror_interface)
> print("See your OS guide for how to do this.")
>@@ -524,15 +533,12 @@ def main():
> if not ovsdb.port_exists(interface):
> print("ERROR: Port %s does not exist." % interface)
> sys.exit(1)
>- if ovsdb.port_exists(mirror_interface):
>- print("ERROR: Mirror port (%s) exists for port %s." %
>- (mirror_interface, interface))
>- sys.exit(1)
>- teardown(db_sock, interface, mirror_interface, tap_created)
>+ teardown(db_sock, interface, mirror_interface, tap_created,
>created_mirror)
> try:
>- ovsdb.make_port(mirror_interface, ovsdb.port_bridge(interface))
>+ if created_mirror:
>+ ovsdb.make_port(mirror_interface, ovsdb.port_bridge(interface))
> ovsdb.bridge_mirror(interface, mirror_interface,
> ovsdb.port_bridge(interface),
> mirror_select_all, mirror_filter=mirror_filter)
Thank you very much! I applied the patch you provided and tested the basic
functionality.
It looks great and effectively solves the problem. The specific steps are as
follows:
ovs-vsctl --may-exist add-port br-tun veth1 -- set interface veth1 type=dpdk --
set interface veth1
options:dpdk-devargs="vdev:virtio_user0,path=/dev/vhost-net,iface=veth1"
[root@compute0-dpdk /]# ovs-tcpdump -i vh-userclient-e5281ddf-c8 --mirror-to
veth1
default timeout is 300
dropped privs to tcpdump
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on veth1, link-type EN10MB (Ethernet), snapshot length 262144 bytes
02:27:13.215588 ARP, Request who-has 10.253.38.66 tell 10.253.38.78, length 46
02:27:14.136472 ARP, Request who-has _gateway (Broadcast) tell 10.253.38.13,
length 42
02:27:14.217607 ARP, Request who-has 10.253.38.66 tell 10.253.38.78, length 46
02:27:14.445831 ARP, Request who-has 10.253.38.68 tell 10.253.38.78, length 46
02:27:15.012926 ARP, Request who-has _gateway (Broadcast) tell master0, length
42
02:27:15.499623 IP6 fc00:0:4:1701::1 > ff02::1:ff00:3: ICMP6, neighbor
solicitation, who has fc00:0:4:1701::3, length 32
Jun Wang
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