| Brendan Gregg | 48fbc3e | 2015-08-18 14:56:14 -0700 | [diff] [blame^] | 1 | Demonstrations of bitehist.py, the Linux eBPF/bcc version. |
| 2 | |
| 3 | This prints a power-of-2 histogram to show the block I/O size distribution. |
| 4 | By default, a summary is printed every five seconds: |
| 5 | |
| 6 | # ./bitehist.py |
| 7 | Tracing... Hit Ctrl-C to end. |
| 8 | |
| 9 | kbytes : count distribution |
| 10 | 0 -> 1 : 0 | | |
| 11 | 2 -> 3 : 0 | | |
| 12 | 4 -> 7 : 26 |************* | |
| 13 | 8 -> 15 : 3 |* | |
| 14 | 16 -> 31 : 5 |** | |
| 15 | 32 -> 63 : 6 |*** | |
| 16 | 64 -> 127 : 7 |*** | |
| 17 | 128 -> 255 : 75 |**************************************| |
| 18 | |
| 19 | kbytes : count distribution |
| 20 | 0 -> 1 : 0 | | |
| 21 | 2 -> 3 : 0 | | |
| 22 | 4 -> 7 : 83 |**************************************| |
| 23 | 8 -> 15 : 2 | | |
| 24 | 16 -> 31 : 6 |** | |
| 25 | 32 -> 63 : 6 |** | |
| 26 | 64 -> 127 : 5 |** | |
| 27 | 128 -> 255 : 21 |********* | |
| 28 | ^C |
| 29 | kbytes : count distribution |
| 30 | 0 -> 1 : 0 | | |
| 31 | 2 -> 3 : 0 | | |
| 32 | 4 -> 7 : 8 |**************************************| |
| 33 | |
| 34 | The first output shows a bimodal distribution. The largest mode of 75 I/O were |
| 35 | between 128 and 255 Kbytes in size, and another mode of 26 I/O were between 4 |
| 36 | and 7 Kbytes in size. |
| 37 | |
| 38 | The next output summary shows the workload is doing more 4 - 7 Kbyte I/O. |
| 39 | |
| 40 | The final output is partial, showing what was measured until Ctrl-C was hit. |
| 41 | |
| 42 | |
| 43 | For an output interval of one second, and three summaries: |
| 44 | |
| 45 | # ./bitehist.py 1 3 |
| 46 | Tracing... Hit Ctrl-C to end. |
| 47 | |
| 48 | kbytes : count distribution |
| 49 | 0 -> 1 : 0 | | |
| 50 | 2 -> 3 : 0 | | |
| 51 | 4 -> 7 : 4 |**************************************| |
| 52 | |
| 53 | kbytes : count distribution |
| 54 | 0 -> 1 : 0 | | |
| 55 | 2 -> 3 : 0 | | |
| 56 | 4 -> 7 : 5 |**************************************| |
| 57 | 8 -> 15 : 0 | | |
| 58 | 16 -> 31 : 0 | | |
| 59 | 32 -> 63 : 1 |******* | |
| 60 | |
| 61 | kbytes : count distribution |
| 62 | 0 -> 1 : 0 | | |
| 63 | 2 -> 3 : 0 | | |
| 64 | 4 -> 7 : 4 |**************************************| |
| 65 | |
| 66 | |
| 67 | Full usage: |
| 68 | |
| 69 | # ./bitehist.py -h |
| 70 | USAGE: ./bitehist.py [interval [count]] |