On 11/30/2016 02:43 AM, Jesper Dangaard Brouer wrote:
Notice the "fib_lookup" cost is still present, even when I use
option "-- -n -N" to create a connected socket. As Eric taught us,
this is because we should use syscalls "send" or "write" on a connected
socket.
In theory, once the data socket is connected, the send_data() call in
src/nettest_omni.c is supposed to use send() rather than sendto().
And indeed, based on a quick check, send() is what is being called,
though it becomes it seems a sendto() system call - with the destination
information NJULL:
write(1, "send\n", 5) = 5
sendto(4, "netperf\0netperf\0netperf\0netperf\0"..., 1024, 0, NULL, 0) =
1024
write(1, "send\n", 5) = 5
sendto(4, "netperf\0netperf\0netperf\0netperf\0"..., 1024, 0, NULL, 0) =
1024
So I'm not sure what might be going-on there.
You can get netperf to use write() instead of send() by adding a
test-specific -I option.
happy benchmarking,
rick
My udp_flood tool[1] cycle through the different syscalls:
taskset -c 2 ~/git/network-testing/src/udp_flood 198.18.50.1 --count $((10**7))
--pmtu 2
ns/pkt pps cycles/pkt
send 473.08 2113816.28 1891
sendto 558.58 1790265.84 2233
sendmsg 587.24 1702873.80 2348
sendMmsg/32 547.57 1826265.90 2189
write 518.36 1929175.52 2072
Using "send" seems to be the fastest option.
Some notes on test: I've forced TX completions to happen on another CPU0
and pinned the udp_flood program (to CPU2) as I want to avoid the CPU
scheduler to move udp_flood around as this cause fluctuations in the
results (as it stress the memory allocations more).
My udp_flood --pmtu option is documented in the --help usage text (see below
signature)
