Netmap gets its own hardware-assisted virtual interface and won't take
over or disrupt the "normal" interface in any way. You can use both
simultaneously.
For kernels with DEV_NETMAP, cxgbe(4) carves out an ncxl<N> interface
(note the 'n' prefix) in the hardware to accompany each cxl<N>
interface. These two ifnet's per port share the same wire but really
are separate interfaces in the hardware and software. Each gets its own
L2 MAC addresses (unicast and multicast), MTU, checksum caps, etc. You
should run netmap on the 'n' interfaces only, that's what they are for.
With this, pkt-gen is able to transmit > 45Mpps out of a single 40G port
of a T580 card. 2 port tx is at ~56Mpps total (28M + 28M) as of now.
Single port receive is at 33Mpps but this is very much a work in
progress. I expect it to be closer to 40Mpps once done. In any case
the current effort can already saturate multiple 10G ports of a T5 card
at the smallest legal packet size. T4 gear is totally untested.
trantor:~# ./pkt-gen -i ncxl0 -f tx -D 00:07:43🆎cd:ef
881.952141 main [1621] interface is ncxl0
881.952250 extract_ip_range [275] range is 10.0.0.1:0 to 10.0.0.1:0
881.952253 extract_ip_range [275] range is 10.1.0.1:0 to 10.1.0.1:0
881.962540 main [1804] mapped 334980KB at 0x801dff000
Sending on netmap:ncxl0: 4 queues, 1 threads and 1 cpus.
10.0.0.1 -> 10.1.0.1 (00:00:00:00:00:00 -> 00:07:43🆎cd:ef)
881.962562 main [1882] Sending 512 packets every 0.000000000 s
881.962563 main [1884] Wait 2 secs for phy reset
884.088516 main [1886] Ready...
884.088535 nm_open [457] overriding ifname ncxl0 ringid 0x0 flags 0x1
884.088607 sender_body [996] start
884.093246 sender_body [1064] drop copy
885.090435 main_thread [1418] 45206353 pps (45289533 pkts in 1001840 usec)
886.091600 main_thread [1418] 45322792 pps (45375593 pkts in 1001165 usec)
887.092435 main_thread [1418] 45313992 pps (45351784 pkts in 1000834 usec)
888.094434 main_thread [1418] 45315765 pps (45406397 pkts in 1002000 usec)
889.095434 main_thread [1418] 45333218 pps (45378551 pkts in 1001000 usec)
890.097434 main_thread [1418] 45315247 pps (45405877 pkts in 1002000 usec)
891.099434 main_thread [1418] 45326515 pps (45417168 pkts in 1002000 usec)
892.101434 main_thread [1418] 45333039 pps (45423705 pkts in 1002000 usec)
893.103434 main_thread [1418] 45324105 pps (45414708 pkts in 1001999 usec)
894.105434 main_thread [1418] 45318042 pps (45408723 pkts in 1002001 usec)
895.106434 main_thread [1418] 45332430 pps (45377762 pkts in 1001000 usec)
896.107434 main_thread [1418] 45338072 pps (45383410 pkts in 1001000 usec)
...
Relnotes: Yes
Sponsored by: Chelsio Communications.
all T4 and T5 based cards and is useful for analyzing TSO, LRO, TOE, and
for general purpose monitoring without tapping any cxgbe or cxl ifnet
directly.
Tracers on the T4/T5 chips provide access to Ethernet frames exactly as
they were received from or transmitted on the wire. On transmit, a
tracer will capture a frame after TSO segmentation, hw VLAN tag
insertion, hw L3 & L4 checksum insertion, etc. It will also capture
frames generated by the TCP offload engine (TOE traffic is normally
invisible to the kernel). On receive, a tracer will capture a frame
before hw VLAN extraction, runt filtering, other badness filtering,
before the steering/drop/L2-rewrite filters or the TOE have had a go at
it, and of course before sw LRO in the driver.
There are 4 tracers on a chip. A tracer can trace only in one direction
(tx or rx). For now cxgbetool will set up tracers to capture the first
128B of every transmitted or received frame on a given port. This is a
small subset of what the hardware can do. A pseudo ifnet with the same
name as the nexus driver (t4nex0 or t5nex0) will be created for tracing.
The data delivered to this ifnet is an additional copy made inside the
chip. Normal delivery to cxgbe<n> or cxl<n> will be made as usual.
/* watch cxl0, which is the first port hanging off t5nex0. */
# cxgbetool t5nex0 tracer 0 tx0 (watch what cxl0 is transmitting)
# cxgbetool t5nex0 tracer 1 rx0 (watch what cxl0 is receiving)
# cxgbetool t5nex0 tracer list
# tcpdump -i t5nex0 <== all that cxl0 sees and puts on the wire
If you were doing TSO, a tcpdump on cxl0 may have shown you ~64K
"frames" with no L3/L4 checksum but this will show you the frames that
were actually transmitted.
/* all done */
# cxgbetool t5nex0 tracer 0 disable
# cxgbetool t5nex0 tracer 1 disable
# cxgbetool t5nex0 tracer list
# ifconfig t5nex0 destroy
filters working. (All other filters - switch without L2 info rewrite,
steer, and drop - were already fully-functional).
Some contrived examples of "switch" filters with L2 rewriting:
# cxgbetool t4nex0 iport 0 dport 80 action switch vlan +9 eport 3
Intercept all packets received on physical port 0 with TCP port 80 as
destination, insert a vlan tag with VID 9, and send them out of port 3.
# cxgbetool t4nex0 sip 192.168.1.1/32 ivlan 5 action switch \
vlan =9 smac aa:bb:cc:dd:ee:ff eport 0
Intercept all packets (received on any port) with source IP address
192.168.1.1 and VLAN id 5, rewrite the VLAN id to 9, rewrite source mac
to aa:bb:cc:dd:ee:ff, and send it out of port 0.
MFC after: 1 week
Reference code that shows how to get a packet's timestamp out of
cxgbe(4). Disabled by default because we don't have a standard way
today to pass this information up the stack.
The timestamp is 60 bits wide and each increment represents 1 tick of
the T4's core clock. As an example, the timestamp granularity is ~4.4ns
for this card:
# sysctl dev.t4nex.0.core_clock
dev.t4nex.0.core_clock: 228125
MFC after: 1 week
