JITTERDEBUGGER(1) | General Commands Manual | JITTERDEBUGGER(1) |
NAME¶
jitterdebugger - measures wake up latenciesSYNOPSIS¶
jitterdebugger [OPTIONS]DESCRIPTION¶
jitterdebugger measures wake up latencies. jitterdebugger starts a thread on each CPU which programs a timer and measures the time it takes from the timer expiring until the thread which set the timer runs again.jitterdebugger default settings will produce a correct meassurement.
The program runs until CTRL-C or SIGTERM is received. The results are printed to STDOUT as JSON encoded string.
OPTIONS¶
- -h, --help
- Show help text and exit.
- -v, --verbose
- Show live updates of the measurments
- -f, --file=FILE
- Write the results into the FILE
- -l, --loops=N
- Run meassurments N times and the terminate jitterdebugger.
- -b, --break=N
- Run jitterdebugger until the N or greater latency has been observed. jitterdebugger will also stop a running tracer by writing 0 to tracing/tracing_on. Furthermore, the value observed will be written to the trace buffers tracing/trace_marker, e.g "Hit latency 249".
- -i, --interval=N
- Set the sleep time between each measuring. The default value is 1000us
- -o, --output=FILE
- Write all samples measured into FILE. This file is binary encoded and can be decoded using jittersamples.
- -a, --affinity=CPUSET
- Set the CPU affinity mask. jitterdebugger starts only meassuring threads on CPUSET,. e.g. 0,2,5-7 starts a thread on first, third and 5, 6 and 7 CPU. May also be set in hexadecimal with '0x' prefix
- -p, --priority=PRI
- Set the priority of the meassuring threads. The default value is 98. Note priority 99 is not available because 99 should only be used for kernel housekeeping tasks.
EXAMPLES¶
# jitterdebugger -v affinity: 0,1 = 2 [0x3] T: 0 ( 614) A: 0 C: 13476 Min: 3 Avg: 3.08 Max: 10 T: 1 ( 615) A: 1 C: 13513 Min: 3 Avg: 3.10 Max: 20 ^C { "cpu": { "0": { "histogram": { "3": 4070, "4": 269, "5": 26, "6": 5, "7": 1, "8": 1, "9": 2, "10": 1 }, "count": 4375, "min": 3, "max": 10, "avg": 3.08 }, "1": { "histogram": { "3": 4002, "4": 320, "5": 22, "6": 4, "7": 2, "8": 1, "10": 2, "11": 1, "16": 2, "20": 1 }, "count": 4357, "min": 3, "max": 20, "avg": 3.10 } } }