I got first pings running over new shared memory interface driver.
Code [1] is still very fragile, but basic packet forwarding works ...
This interface defines master/slave relationship.
Some characteristics:
- slave can run inside un-privileged containers
- master can run inside container, but it requires global PID namespace and
PTRACE capability
- initial connection is done over the unix socket, so for container networking
socket file needs to be mapped into container
- slave allocates shared memory for descriptor rings and passes FD to master
- slave is ring producer for both tx and rx, it fills rings with either full
or empty buffers
- master is ring consumer, it reads descriptors and executes memcpy from/to
buffer
- process_vm_readv, process_vm_writev linux system calls are used for copy of
data directly between master and slave VM (it avoids 2nd memcpy)
- process_vm_* system calls are executed once per vector of packets
- from security perspective, slave doesn’t have access to master memory
- currently polling-only
- reconnection should just work - slave runs reconnect process in case when
master disappears
TODO:
- multi-queue
- interrupt mode (likely simple byte read/write to file descriptor)
- lightweight library to be used for non-VPP clients
- L3 mode ???
- perf tuning
- user-mode memcpy - master maps slave buffer memory directly…
- docs / specification
At this point I would really like to hear feedback from people,
specially from the usability side.
config is basically:
create memif socket /path/to/unix_socket.file [master|slave]
set int state memif0 up
DBGvpp# show interfaces
Name Idx State Counter Count
local0 0 down
memif0 1 up
DBGvpp# show interfaces address
local0 (dn):
memif0 (up):
172.16.0.2/24
DBGvpp# ping 172.16.0.1
64 bytes from 172.16.0.1: icmp_seq=1 ttl=64 time=18.4961 ms
64 bytes from 172.16.0.1: icmp_seq=2 ttl=64 time=18.4282 ms
64 bytes from 172.16.0.1: icmp_seq=3 ttl=64 time=26.4333 ms
64 bytes from 172.16.0.1: icmp_seq=4 ttl=64 time=18.4255 ms
64 bytes from 172.16.0.1: icmp_seq=5 ttl=64 time=14.4133 ms
Statistics: 5 sent, 5 received, 0% packet loss
DBGvpp# show interfaces
Name Idx State Counter Count
local0 0 down
memif0 1 up rx packets
5
rx bytes
490
tx packets
5
tx bytes
490
drops
5
ip4
5
[1] https://gerrit.fd.io/r/#/c/5004/
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