| Demonstrations of bitehist.py, the Linux eBPF/bcc version. |
| |
| This prints a power-of-2 histogram to show the block I/O size distribution. |
| A summary is printed after Ctrl-C is hit. |
| |
| # ./bitehist.py |
| Tracing... Hit Ctrl-C to end. |
| ^C |
| kbytes : count distribution |
| 0 -> 1 : 3 | | |
| 2 -> 3 : 0 | | |
| 4 -> 7 : 211 |********** | |
| 8 -> 15 : 0 | | |
| 16 -> 31 : 0 | | |
| 32 -> 63 : 0 | | |
| 64 -> 127 : 1 | | |
| 128 -> 255 : 800 |**************************************| |
| |
| This output shows a bimodal distribution. The largest mod of 800 I/O were |
| between 128 and 255 Kbytes in size, and another mode of 211 I/O were between |
| 4 and 7 Kbytes in size. |
| |
| Understanding this distribution is useful for characterizing workloads and |
| understanding performance. The existence of this distribution is not visible |
| from averages alone. |
