This report was generated with the measure-analysis.py script.
JSON formated measures were imported in the measures folder using the import functionnality of the script, this report was then generated using these measures.
Metadata is included with the measures, such as the kernel version used, the boot parameters passed, various others parameters specific to the measure, etc...
Measures measuring the same propriety are grouped together in tables and graphs, and are identified by their diverging metadatas. This is useful to analyse the effect of specific parameters on the measured propriety.
### Description of the metadata associated to each test
***dev**: Device on which the tests were run
***ker**: Linux kernel version used
***prio**: Priority of the real-time thread
***i**: Interval between each packet transmission
***boot_p**: Boot Parameters passed to u-boot
***delta**: ETF qdisc delta value
***load**: External device and processor load during the test
***duration**: Duration of the test
***speed**: Ethernet speed in Mb/s
***etf_offset**: When a packet\s txtime is scheduled, the txtime set is the current time offset by etf_offset
***route**: How the boards are connected. switch means they are connected by a switch (cheap, unmanaged), E2E
***qdisc**: qdisc used to send packets
***client**: Device which sent the packets
***server**: Device which received the packets
***XDP**: Were XDP sockets used
***delay**: Callback schedule delay in us
### cyclictest_wake-up_latency results
Uses cyclictest from the rt-tests test suite to measure wake-up latency. A real-time thread is run on CPU1, and wakes up at a regular interval (specified by the interval parameter) using clock_nanosleep. It then uses clock_gettime and computes the difference between the scheduled wake-up time and the effective wake-up time measured by clock_gettime.
The command used is: cyclictest -p `prio` -a1 -t1 -n -h 200 -q -i `interval`
**Common test metadata:** Task priority: 98, Interval: 200us, Boot Parameters: isolcpus,rcu_nocbs,irqaffinity, ETF qdisc delta: None, Device and processor load: None, qdisc: pfifo_fast, XDP: no
Metadata | Minimum | Maximum | Average | Standard deviation | Lost packets
Two A20 boards are connected end to end with an ethernet cable to a shuttle. All devices are synchronized with PTP. The shuttle sends packets containing timestamps to the boards, and the boards emit a signal at the given timestamp. A logic analyzer measures the variation difference between the signals of the two boards.
A UDP packet is periodically sent from one device to another using a real time thread. The receiving device calculates the intervals between the packets it receives, and sees how much it differs from the scheduled interval.
Same setup as packet jitter measures. Client and server are synchronized with PTP, the client checks the time before sending the packet, and sends it in the packet. The servechecks the time after receiving the packet, and records the difference between both timestamps to calculate latency.
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This report was generated with the measure-analysis.py script.
JSON formated measures were imported in the measures folder using the import functionnality of the script, this report was then generated using these measures.
Metadata is included with the measures, such as the kernel version used, the boot parameters passed, various others parameters specific to the measure, etc...
Measures measuring the same propriety are grouped together in tables and graphs, and are identified by their diverging metadatas. This is useful to analyse the effect of specific parameters on the measured propriety.
#Metadata
##dev
Default value: A20
Short name: Device
Description: Device on which the tests were run
##ker
Default value: 5.6
Short name: Linux kernel version
Description: Linux kernel version used
##prio
Default value: 98
Short name: Task priority
Description: Priority of the real-time thread
##i
Default value: 1000us
Short name: Interval
Description: Interval between each packet transmission
##boot_p
Default value: isolcpus,rcu_nocbs,irqaffinity
Short name: Boot Parameters
Description: Boot Parameters passed to u-boot
##delta
Default value: None
Short name: ETF qdisc delta
Description: ETF qdisc delta value
##load
Default value: None
Short name: Device and processor load
Description: External device and processor load during the test
##duration
Default value: 0h00
Short name: Test duration
Description: Duration of the test
##speed
Default value: 1000
Short name: Speed (Mb/s)
Description: Ethernet speed in Mb/s
##etf_offset
Default value: 500us
Short name: ETF offset
Description: When a packet\s txtime is scheduled, the txtime set is the current time offset by etf_offset
##route
Default value: E2E
Short name: Packet route
Description: How the boards are connected. switch means they are connected by a switch (cheap, unmanaged), E2E
Description: Uses cyclictest from the rt-tests test suite to measure wake-up latency. A real-time thread is run on CPU1, and wakes up at a regular interval (specified by the interval parameter) using clock_nanosleep. It then uses clock_gettime and computes the difference between the scheduled wake-up time and the effective wake-up time measured by clock_gettime.
The command used is: cyclictest -p `prio` -a1 -t1 -n -h 200 -q -i `interval`
##packet_jitter
Ignored metadata: delay,dev
Description: A UDP packet is periodically sent from one device to another using a real time thread. The receiving device calculates the intervals between the packets it receives, and sees how much it differs from the scheduled interval.
##packet_latency
Ignored metadata: delay,dev
Description: Same setup as packet jitter measures. Client and server are synchronized with PTP, the client checks the time before sending the packet, and sends it in the packet. The servechecks the time after receiving the packet, and records the difference between both timestamps to calculate latency.
##packet_rx_timestamps
Ignored metadata: delay,client,server
Description: An UDP packet is periodically sent from one board to another using a real time thread. The receiving board uses the SO_TIMESTAMPING option to see when the packet entered the kernel, and generates timestamps with clock_gettime once the packets enters userspace to compute the time the packet spent in kernel space.
##packet_tx_timestamps
Ignored metadata: delay,client,server
Description: Similar to packet_rx_timestamps, but on the transmitting board.
##packet_rtt
Ignored metadata: delay,dev
Description: A UDP packet is periodically sent from one board to another and sent back as soon as it arrives using a real time thread. The round trip time is computed with clock_gettime on the transmitting board.
##shuttle_a20_signal_jitter
Ignored metadata: dev,client,server
Description: Two A20 boards are connected end to end with an ethernet cable to a shuttle. All devices are synchronized with PTP. The shuttle sends packets containing timestamps to the boards, and the boards emit a signal at the given timestamp. A logic analyzer measures the variation difference between the signals of the two boards.
##shuttle_signal_jitter
Ignored metadata: delay,client,server,dev
Description: Two shuttles connected end to end with an ethernet cable and synchronized with PTP emit signals, and a logic analyzer measures variation in those signals, similar to "Shuttle controlled A20 signal output jitter" measures