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hardirqs_example.txt
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hardirqs_example.txt
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Demonstrations of hardirqs, the Linux eBPF/bcc version.
This program traces hard interrupts (irqs), and stores timing statistics
in-kernel for efficiency. For example:
# ./hardirqs
Tracing hard irq event time... Hit Ctrl-C to end.
^C
HARDIRQ TOTAL_usecs
callfuncsingle0 2
callfuncsingle5 5
callfuncsingle6 5
callfuncsingle7 21
blkif 66
timer7 84
resched5 94
resched0 97
resched3 102
resched7 111
resched6 255
timer3 362
resched4 367
timer5 474
timer1 529
timer6 679
timer2 746
timer4 943
resched1 1048
timer0 1558
resched2 1750
eth0 11441
The HARDIRQ column prints the interrupt action name. While tracing, the eth0
hard irq action ran for 11441 microseconds (11 milliseconds) in total.
Many other interrupts are visible in the output: this is an 8 CPU system, and
some of these interrupts have a separate action per-CPU (eg, "timer",
"resched").
An interval can be provided, and also optionally a count. Eg, printing output
every 1 second, and including timestamps (-T):
# ./hardirqs -T 1 3
Tracing hard irq event time... Hit Ctrl-C to end.
22:16:14
HARDIRQ TOTAL_usecs
callfuncsingle0 2
callfuncsingle7 5
callfuncsingle3 5
callfuncsingle2 5
callfuncsingle6 6
callfuncsingle1 11
resched0 32
blkif 51
resched5 71
resched7 71
resched4 72
resched6 82
timer7 172
resched1 187
resched2 236
timer3 252
resched3 282
timer1 320
timer2 374
timer6 396
timer5 427
timer4 470
timer0 1430
eth0 7498
22:16:15
HARDIRQ TOTAL_usecs
callfuncsingle7 6
callfuncsingle5 11
callfuncsingle4 13
timer2 17
callfuncsingle6 18
resched0 21
blkif 33
resched3 40
resched5 60
resched4 69
resched6 70
resched7 74
timer7 86
resched2 91
timer3 134
resched1 293
timer5 354
timer1 433
timer6 497
timer4 1112
timer0 1768
eth0 6972
22:16:16
HARDIRQ TOTAL_usecs
callfuncsingle7 5
callfuncsingle3 5
callfuncsingle2 6
timer3 10
resched0 18
callfuncsingle4 22
resched5 27
resched6 44
blkif 45
resched7 65
resched4 69
timer4 77
resched2 97
timer7 98
resched3 103
timer2 169
resched1 226
timer5 525
timer1 691
timer6 697
timer0 1415
eth0 7152
This can be useful for quantifying where CPU cycles are spent among the hard
interrupts (summarized as the %irq column from mpstat(1)). The output above
shows that most time was spent processing for eth0 (network interface), which
was around 7 milliseconds per second (total across all CPUs).
Note that the time spent among the "timer" interrupts was low, and usually less
than one microsecond per second. Here's the hardirq per-second output when the
perf tool is performing a 999 Hertz CPU profile ("perf record -F 999 -a ..."):
22:13:59
HARDIRQ TOTAL_usecs
callfuncsingle7 5
callfuncsingle5 5
callfuncsingle3 6
callfuncsingle4 7
callfuncsingle6 19
blkif 66
resched0 66
resched2 82
resched7 87
resched3 96
resched4 118
resched5 120
resched6 130
resched1 230
timer3 946
timer1 1981
timer7 2618
timer5 3063
timer6 3141
timer4 3511
timer2 3554
timer0 5044
eth0 16015
This sheds some light into the CPU overhead of the perf profiler, which cost
around 3 milliseconds per second. Note that I'm usually profiling at a much
lower rate, 99 Hertz, which looks like this:
22:22:12
HARDIRQ TOTAL_usecs
callfuncsingle3 5
callfuncsingle6 5
callfuncsingle5 22
blkif 46
resched6 47
resched5 57
resched4 66
resched7 78
resched2 97
resched0 214
timer2 326
timer0 498
timer5 536
timer6 576
timer1 600
timer4 982
resched1 1315
timer7 1364
timer3 1825
resched3 5708
eth0 9743
Much lower (and remember to compare this to the baseline). Note that perf has
other overheads (non-irq CPU cycles, file system storage).
The distribution of interrupt run time can be printed as a histogram with the -d
option. Eg:
# ./hardirqs -d
Tracing hard irq event time... Hit Ctrl-C to end.
^C
hardirq = 'callfuncsingle1'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 0 | |
4096 -> 8191 : 0 | |
8192 -> 16383 : 1 |****************************************|
hardirq = 'callfuncsingle0'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 1 |****************************************|
hardirq = 'callfuncsingle3'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 0 | |
4096 -> 8191 : 3 |****************************************|
hardirq = 'callfuncsingle2'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 0 | |
4096 -> 8191 : 2 |****************************************|
hardirq = 'callfuncsingle5'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 0 | |
4096 -> 8191 : 5 |****************************************|
hardirq = 'callfuncsingle4'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 0 | |
4096 -> 8191 : 6 |****************************************|
hardirq = 'callfuncsingle7'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 0 | |
4096 -> 8191 : 4 |****************************************|
hardirq = 'callfuncsingle6'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 0 | |
4096 -> 8191 : 4 |****************************************|
hardirq = 'eth0'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 5102 |********* |
1024 -> 2047 : 20617 |****************************************|
2048 -> 4095 : 4832 |********* |
4096 -> 8191 : 12 | |
hardirq = 'timer7'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 9 |*** |
2048 -> 4095 : 70 |***************************** |
4096 -> 8191 : 94 |****************************************|
hardirq = 'timer6'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 1 | |
2048 -> 4095 : 86 |*********** |
4096 -> 8191 : 295 |****************************************|
8192 -> 16383 : 28 |*** |
hardirq = 'timer5'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 1 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 137 |****************************************|
4096 -> 8191 : 123 |*********************************** |
8192 -> 16383 : 8 |** |
hardirq = 'timer4'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 46 |********* |
4096 -> 8191 : 198 |****************************************|
8192 -> 16383 : 49 |********* |
hardirq = 'timer3'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 4 | |
2048 -> 4095 : 210 |****************************************|
4096 -> 8191 : 186 |*********************************** |
hardirq = 'timer2'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 245 |****************************************|
4096 -> 8191 : 227 |************************************* |
8192 -> 16383 : 6 | |
hardirq = 'timer1'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 6 |* |
2048 -> 4095 : 112 |************************ |
4096 -> 8191 : 181 |****************************************|
8192 -> 16383 : 7 |* |
hardirq = 'timer0'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 0 | |
4096 -> 8191 : 887 |****************************************|
8192 -> 16383 : 92 |**** |
hardirq = 'blkif'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 0 | |
4096 -> 8191 : 9 |****************************************|
8192 -> 16383 : 7 |******************************* |
16384 -> 32767 : 2 |******** |
hardirq = 'resched4'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 104 |****************************************|
2048 -> 4095 : 80 |****************************** |
hardirq = 'resched5'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 27 |***** |
1024 -> 2047 : 216 |****************************************|
2048 -> 4095 : 27 |***** |
4096 -> 8191 : 1 | |
hardirq = 'resched6'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 480 |******************* |
1024 -> 2047 : 1003 |****************************************|
2048 -> 4095 : 64 |** |
hardirq = 'resched7'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 46 |********* |
1024 -> 2047 : 190 |****************************************|
2048 -> 4095 : 42 |******** |
hardirq = 'resched0'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 11 |**** |
1024 -> 2047 : 100 |****************************************|
2048 -> 4095 : 23 |********* |
hardirq = 'resched1'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 96 |******** |
1024 -> 2047 : 462 |****************************************|
2048 -> 4095 : 36 |*** |
hardirq = 'resched2'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 120 |************************** |
1024 -> 2047 : 183 |****************************************|
2048 -> 4095 : 41 |******** |
hardirq = 'resched3'
usecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 0 | |
128 -> 255 : 0 | |
256 -> 511 : 0 | |
512 -> 1023 : 0 | |
1024 -> 2047 : 789 |****************************************|
2048 -> 4095 : 39 |* |
USAGE message:
# ./hardirqs -h
usage: hardirqs [-h] [-T] [-N] [-d] [interval] [count]
Summarize hard irq event time as histograms
positional arguments:
interval output interval, in seconds
count number of outputs
optional arguments:
-h, --help show this help message and exit
-T, --timestamp include timestamp on output
-N, --nanoseconds output in nanoseconds
-d, --dist show distributions as histograms
examples:
./hardirqs # sum hard irq event time
./hardirqs -d # show hard irq event time as histograms
./hardirqs 1 10 # print 1 second summaries, 10 times
./hardirqs -NT 1 # 1s summaries, nanoseconds, and timestamps