igc: Add support for multiple in-flight TX timestamps
Add support for using the four sets of timestamping registers that
i225/i226 have available for TX.
In some workloads, where multiple applications request hardware
transmission timestamps, it was possible that some of those requests
were denied because the only in use register was already occupied.
This is also in preparation to future support for hardware
timestamping with multiple PTP domains. With multiple domains chances
of multiple TX timestamps being requested at the same time increase.
Before:
$ sudo ./ntpperf -i enp3s0 -m 10:22:22:22:22:21 -d 192.168.1.3 -s 172.18.0.0/16 -I -H -o 37
| responses | TX timestamp offset (ns)
rate clients | lost invalid basic xleave | min mean max stddev
1000 100 0.00% 0.00% 0.00% 100.00% +1 +41 +73 13
1500 150 0.00% 0.00% 0.00% 100.00% +9 +49 +87 15
2250 225 0.00% 0.00% 0.00% 100.00% +9 +42 +79 13
3375 337 0.00% 0.00% 0.00% 100.00% +11 +46 +81 13
5062 506 0.00% 0.00% 0.00% 100.00% +7 +44 +80 13
7593 759 0.00% 0.00% 0.00% 100.00% +9 +44 +79 12
11389 1138 0.00% 0.00% 0.00% 100.00% +14 +51 +87 13
17083 1708 0.00% 0.00% 0.00% 100.00% +1 +41 +80 14
25624 2562 0.00% 0.00% 0.00% 100.00% +11 +50 +5107 51
38436 3843 0.00% 0.00% 0.00% 100.00% -2 +36 +7843 38
57654 5765 0.00% 0.00% 0.00% 100.00% +4 +42 +10503 69
86481 8648 0.00% 0.00% 0.00% 100.00% +11 +54 +5492 65
129721 12972 0.00% 0.00% 0.00% 100.00% +31 +2680 +6942 2606
194581 16384 16.79% 0.00% 0.87% 82.34% +73 +4444 +15879 3116
291871 16384 35.05% 0.00% 1.53% 63.42% +188 +5381 +17019 3035
437806 16384 54.95% 0.00% 2.55% 42.50% +233 +6302 +13885 2846
After:
$ sudo ./ntpperf -i enp3s0 -m 10:22:22:22:22:21 -d 192.168.1.3 -s 172.18.0.0/16 -I -H -o 37
| responses | TX timestamp offset (ns)
rate clients | lost invalid basic xleave | min mean max stddev
1000 100 0.00% 0.00% 0.00% 100.00% -20 +12 +43 13
1500 150 0.00% 0.00% 0.00% 100.00% -23 +18 +57 14
2250 225 0.00% 0.00% 0.00% 100.00% -2 +33 +67 13
3375 337 0.00% 0.00% 0.00% 100.00% +1 +38 +76 13
5062 506 0.00% 0.00% 0.00% 100.00% +9 +52 +93 14
7593 759 0.00% 0.00% 0.00% 100.00% +11 +47 +82 13
11389 1138 0.00% 0.00% 0.00% 100.00% -9 +27 +74 13
17083 1708 0.00% 0.00% 0.00% 100.00% -13 +25 +66 14
25624 2562 0.00% 0.00% 0.00% 100.00% -8 +28 +65 13
38436 3843 0.00% 0.00% 0.00% 100.00% -13 +28 +69 13
57654 5765 0.00% 0.00% 0.00% 100.00% -11 +32 +71 14
86481 8648 0.00% 0.00% 0.00% 100.00% +2 +44 +83 14
129721 12972 15.36% 0.00% 0.35% 84.29% -2 +2248 +22907 4252
194581 16384 42.98% 0.00% 1.98% 55.04% -4 +5278 +65039 5856
291871 16384 54.33% 0.00% 2.21% 43.46% -3 +6306 +22608 5665
We can see that with 4 registers, as expected, we are able to handle a
increasing number of requests more consistently, but as soon as all
registers are in use, the decrease in quality of service happens in a
sharp step.
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@intel.com>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
projects / platform / kernel / linux-rpi.git / commit