blkalgn: add support

[dkruces]

Add blkalgn support to trace block I/Os and report Granularity and Alignment.

---

Note: I chose not to create a separate Makefile (for now) as mentioned in the README. This first approach is to gather feedback on the tool and code.

A previous version of the tool using bcc/Python was 'introduced' here:
#4813

Output example:

sudo blkalgn --disk nvme0n1 --ops Write --trace
Tracing block device I/O... Hit Ctrl-C to end.
DISK       OPS        FLAGS    LEN      LBA                   PID        COMM             ALGN
nvme0n1    0x801      Write    131072   0                     0          fio              131072
nvme0n1    0x801      Write    131072   0                     0          fio              131072
nvme0n1    0x801      Write    131072   0                     0          fio              131072
nvme0n1    0x801      Write    131072   0                     0          fio              131072
nvme0n1    0x801      Write    131072   0                     0          fio              131072
nvme0n1    0x801      Write    131072   0                     0          fio              131072
nvme0n1    0x801      Write    131072   0                     0          fio              131072
nvme0n1    0x801      Write    131072   0                     0          fio              131072
nvme0n1    0x801      Write    131072   0                     0          fio              131072

{...}

nvme0n1    0x801      Write    4096     0                     0          fio              4096
nvme0n1    0x801      Write    4096     0                     0          fio              4096
nvme0n1    0x801      Write    4096     0                     0          fio              4096
^C

I/O Granularity Histogram for Device nvme0n1
Total I/Os: 187
     sector        : count     distribution
        8          : 12       |****                                    |
        64         : 25       |**********                              |
        128        : 50       |********************                    |
        256        : 100      |****************************************|

I/O Alignment Histogram for Device nvme0n1
     bytes               : 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       : 12       |****                                    |
      8192 -> 16383      : 0        |                                        |
     16384 -> 32767      : 0        |                                        |
     32768 -> 65535      : 25       |**********                              |
     65536 -> 131071     : 50       |********************                    |
    131072 -> 262143     : 100      |****************************************|
    ```
    
    Test case for the above results
    
    ```sh
sudo fio --name=deterministic_io_test --size=128K --bs=128K --rw=randwrite --numjobs=1 --iodepth=1 --filename=/dev/nvme0n1 --loop 100
sudo fio --name=deterministic_io_test --size=64K --bs=64K --rw=randwrite --numjobs=1 --iodepth=1 --filename=/dev/nvme0n1 --loop 50
sudo fio --name=deterministic_io_test --size=32K --bs=32K --rw=randwrite --numjobs=1 --iodepth=1 --filename=/dev/nvme0n1 --loop 25
sudo fio --name=deterministic_io_test --size=512 --bs=512 --rw=randwrite --numjobs=1 --iodepth=1 --filename=/dev/nvme0n1 --loop 12

Help output:

sudo blkalgn --help
Usage: blkalgn [OPTION...]
BPF blkalgn application.

It traces block I/O operations and reports I/O granularity and
alignment.

USAGE: ./blkalgn [-d <disk>] [-o <ops>] [-j <output>] [-t] [-v]

 -d, --disk=DISK            Trace this disk only
 -j, --json=JSON            Output to JSON
 -o, --ops=OPS              Trace this ops only
 -t, --trace                Enable trace output
 -v, --verbose              Verbose debug output
 -?, --help                 Give this help list
     --usage                Give a short usage message
 -V, --version              Print program version

Mandatory or optional arguments to long options are also mandatory or optional
for any corresponding short options.

Report bugs to <[email protected]>.

The tool can trace I/Os, filter by device and/or block operation, and generate an output file to JSON with captured information. I think, because of the use of a JSON external library, it requires to have a separate Makefile as stated in the README section. Can you provide feedback on this? Note that it also depends on math.h for log2l in user space.

[dkruces]

Changes:

• Add json-c development headers to Fedora Dockerfile.
• Add blkalgn to clean Makefile target.
• Rename *_LEN defines and cleanup unused event fields.

[dkruces]

Kindly ping. Any feedback on this?