on Jun 5, 2017 11:10 AM. Last modified by One Pulse Per Second (1PPS) is a time synchronization feature that allows the adapter to be able to send or receive 1 pulse per second on a dedicated pin on the adapter card.
The supported ASICs are ConnectX-4 or later, using MLNX_OFED 4.1 or later. Only one pin is supported and could be configured as 1PPS in or 1PPS out.
The adapter to be used with this feature, has an SMA connector and has the P/N of MCX556A-EDAM (FSI card).
testptp.c is a short script that can help you test time syncronization features such as One Pulse Per Second (1PPS).
References
Setup
In this example we have two servers connected back to back with the 1PPS pin on the adapter. One server will generate the 1PPS signal (1PPS out), while the other server will be receiving the 1PPS (1PPS in).
Installation
1. There are several location to download the script, make sure to download one of the latest ones. here is an example.
https://www.mjmwired.net/kernel/Documentation/ptp/testptp.c
2. Install the script using:
# gcc -Wall -lrt testptp.c -o testptp
3. Get help
# ./testptp -h
usage: testptp [options]
-a val request a one-shot alarm after 'val' seconds
-A val request a periodic alarm every 'val' seconds
-c query the ptp clock's capabilities
-d name device to open
-e val read 'val' external time stamp events
-f val adjust the ptp clock frequency by 'val' ppb
-g get the ptp clock time
-h prints this message
-i val index for event/trigger
-k val measure the time offset between system and phc clock
for 'val' times (Maximum 25)
-l list the current pin configuration
-L pin,val configure pin index 'pin' with function 'val'
the channel index is taken from the '-i' option
'val' specifies the auxiliary function:
0 - none
1 - external time stamp
2 - periodic output
-p val enable output with a period of 'val' nanoseconds
-P val enable or disable (val=1|0) the system clock PPS
-s set the ptp clock time from the system time
-S set the system time from the ptp clock time
-t val shift the ptp clock time by 'val' seconds
-T val set the ptp clock time to 'val' seconds
Configuration
1. Make sure to install MLNX_OFED 4.1 or above, on your server.
2. Get the Time Synchronization support on the relevant port via ethtool. In this example, we are using PTP Clock 3. The device path will be /dev/ptp3
# ethtool -T ens2
Time stamping parameters for ens2:
Capabilities:
hardware-transmit (SOF_TIMESTAMPING_TX_HARDWARE)
software-transmit (SOF_TIMESTAMPING_TX_SOFTWARE)
hardware-receive (SOF_TIMESTAMPING_RX_HARDWARE)
software-receive (SOF_TIMESTAMPING_RX_SOFTWARE)
software-system-clock (SOF_TIMESTAMPING_SOFTWARE)
hardware-raw-clock (SOF_TIMESTAMPING_RAW_HARDWARE)
PTP Hardware Clock: 3
Hardware Transmit Timestamp Modes:
on (HWTSTAMP_TX_ON)
one-step-sync (HWTSTAMP_TX_ONESTEP_SYNC)
Hardware Receive Filter Modes:
all (HWTSTAMP_FILTER_ALL)
some (HWTSTAMP_FILTER_SOME)
3. Query the ptp clock's capabilities.
# ./testptp -d /dev/ptp3 -c
capabilities:
100000000 maximum frequency adjustment (ppb)
0 programmable alarms
1 external time stamp channels
1 programmable periodic signals
1 pulse per second
1 programmable pins
4. Check the current pin configuration
# ./testptp -d /dev/ptp3 -l
name mlx5_pps0 index 0 func 0 chan 0
- Name: Pin name.
- index: The Pin number. In case of ConnectX-4, we support only one Pin, therefore it will always be zero.
- func (function): The pin Configuration
0 - none
1 - 1PPS In
2 - 1PPS Out (periodic output)
- chan (channel) - Reserved field.
The parameters are taken from ptp_pin_desc in ptp_clock.h .
5. On one server, set 1PPS in on the adapter, use pin index 0 and -L flag and value 1. Check the func value was changed.
# ./testptp -d /dev/ptp3 -l
name mlx5_pps0 index 0 func 0 chan 0
# ./testptp -d /dev/ptp3 -L 0,1
set pin function okay
# ./testptp -d /dev/ptp3 -l
name mlx5_pps0 index 0 func 1 chan 0
6. On the second server, set 1PPS out on the adapter, use pin index 0 the -L flag and value 2. Check the func value was changed.
# ./testptp -d /dev/ptp3 -l
name mlx5_pps0 index 0 func 0 chan 0
# ./testptp -d /dev/ptp3 -L 0,2
set pin function okay
# ./testptp -d /dev/ptp3 -l
name mlx5_pps0 index 0 func 2 chan 0
7. On the 1PPS in server, set the maximum number of events to be set/handled by the application.
#./testptp -d /dev/ptp3 -e 1000
external time stamp request okay
...
8. On the 1PPS out server, enabled 1PPS using -p 1000000000 (in nsec)
# ./testptp -d /dev/ptp3 -p 1000000000
periodic output request okay
9. Check the 1PPS in server to get the time stamp.
# ./testptp -d /dev/ptp3 -e 1000
external time stamp request okay
event index 0 at 1496670401.396081197
event index 0 at 1496670402.396060918
event index 0 at 1496670403.396040626
event index 0 at 1496670404.396020335
event index 0 at 1496670405.396000037
event index 0 at 1496670406.395979745
event index 0 at 1496670407.395959460
event index 0 at 1496670408.395939174
event index 0 at 1496670409.395918883
event index 0 at 1496670410.395898597
10. Some applications may need to read the timestamp from a file. To write the time stamps into a file, enable the pps_enable sysfs parameter in the 1 PPS in server
# echo 1 > /sys/class/ptp/ptp3/pps_enable
# watch -n 1 'cat /sys/class/pps/pps0/assert'
No changes are needed on the other server.
To disable it again and get the timestamps to the terminal, run:
# echo 0 > /sys/class/ptp/ptp3/pps_enable
# ./testptp -d /dev/ptp3 -e 1000
Command Summary
1PPS in
ethtool -T ens2
./testptp -d /dev/ptp3 -c
./testptp -d /dev/ptp3 -l
./testptp -d /dev/ptp3 -L 0,0
./testptp -d /dev/ptp3 -l
./testptp -d /dev/ptp3 -L 0,1
./testptp -d /dev/ptp3 -e 1000
echo 1 > /sys/class/ptp/ptp3/pps_enable
watch -n 1 'cat /sys/class/pps/pps0/assert'
echo 0 > /sys/class/ptp/ptp3/pps_enable
./testptp -d /dev/ptp3 -e 1000
1PPS out
ethtool -T ens2
./testptp -d /dev/ptp3 -c
./testptp -d /dev/ptp3 -l
./testptp -d /dev/ptp3 -L 0,0
./testptp -d /dev/ptp3 -l
./testptp --help
./testptp -d /dev/ptp3 -L 0,2
./testptp -d /dev/ptp3 -p 1000000000
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