Linux ZIO

ZIO: The Ultimate Linux Kernel I/O Framework

Handbook

Setup

aptitude install linux-headers-amd64
git clone git://ohwr.org/misc/zio.git
cd zio
make

README:

insmod zio.ko
insmod drivers/zio-zero.ko
lsmod | grep zio
zio_zero               24576  0
zio                    81920  7 zio_zero

dmesg:

[5431949.898785] zio-core had been loaded
[5432090.752090] zzero zzero-0000: device loaded

Operation

Without access to appropriate hardware, let’s use channels from the zero device.

zio-manual:

The zero device is a software-driven input and output device, it is used for demonstration and stress-testing. It behaves like /dev/zero, /dev/null and similar devices, but it inputs and outputs ZIO blocks.

README:

zio-zero has three channel sets. cset 0 has three channels.
They simulate three analog inputs, 8-bits per sample.

     channel 0: returns zero forever
     channel 1: returns random numbers
     channel 2: returns a sawtooth signal (0 to 255 and back)

[...]

To read data you can just cat, or "od -t x1" the data device.
To get control information meta-information) together with data, you
can use the "zio-dump" user-space utility, in this directory.

Examples:

./tools/zio-dump /dev/zio/zzero-0000-0-2-* | more
Ctrl: version 1.2, trigger user, dev zzero-0000, cset 0, chan 2
Ctrl: alarms 0x00 0x00
Ctrl: seq 11462719, n 16, size 1, bits 8, flags 01000001 (little-endian)
Ctrl: stamp 1447478540.733762335 (0)
Data: e0 e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef

./tools/zio-cat-file /dev/zio/zzero-0000-0-2-data 10 | od -t x1z
0000000 c0 c1 c2 c3 c4 c5 c6 c7 c8 c9 ca cb cc cd ce cf  >................<
0000020 d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc dd de df  >................<
0000040 e0 e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef  >................<
0000060 f0 f1 f2 f3 f4 f5 f6 f7 f8 f9 fa fb fc fd fe ff  >................<
0000100 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f  >................<
0000120 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f  >................<
0000140 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f  > !"#$%&'()*+,-./<
0000160 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f  >0123456789:;<=>?<
0000200 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f  >@ABCDEFGHIJKLMNO<
0000220 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f  >PQRSTUVWXYZ[\]^_<

./tools/zio-cat-file /dev/zio/zzero-0000-0-2-data 10 | od -A n -t x1
 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
 70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f
 80 81 82 83 84 85 86 87 88 89 8a 8b 8c 8d 8e 8f
 90 91 92 93 94 95 96 97 98 99 9a 9b 9c 9d 9e 9f
 a0 a1 a2 a3 a4 a5 a6 a7 a8 a9 aa ab ac ad ae af
 b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 ba bb bc bd be bf
 c0 c1 c2 c3 c4 c5 c6 c7 c8 c9 ca cb cc cd ce cf
 d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc dd de df
 e0 e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef
 f0 f1 f2 f3 f4 f5 f6 f7 f8 f9 fa fb fc fd fe ff

Throughput:

time ./tools/zio-cat-file /dev/zio/zzero-0000-0-2-data 180000 | od -A n -t x1 | wc -w
./tools/zio-cat-file: /dev/zio/zzero-0000-0-2-data: no mmap available
./tools/zio-cat-file: trasferred 180000 blocks, 2880000 bytes, 1.033464 secs
2880000

real        0m1.062s
user        0m1.288s
sys 0m0.660s

=> 2.8 million bytes per second. This is 2.8 MHz, right?

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