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Diffstat (limited to 'cddl/contrib/dtracetoolkit/Examples/iopending_example.txt')
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diff --git a/cddl/contrib/dtracetoolkit/Examples/iopending_example.txt b/cddl/contrib/dtracetoolkit/Examples/iopending_example.txt new file mode 100644 index 0000000..f4bc822 --- /dev/null +++ b/cddl/contrib/dtracetoolkit/Examples/iopending_example.txt @@ -0,0 +1,126 @@ +The following is a demonstration of the iopending tool, + +Here we run it with a sample interval of 1 second, + + # iopending 1 + Tracing... Please wait. + 2006 Jan 6 20:21:59, load: 0.02, disk_r: 0 KB, disk_w: 0 KB + + value ------------- Distribution ------------- count + < 0 | 0 + 0 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1010 + 1 | 0 + + 2006 Jan 6 20:22:00, load: 0.03, disk_r: 0 KB, disk_w: 0 KB + + value ------------- Distribution ------------- count + < 0 | 0 + 0 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1000 + 1 | 0 + + 2006 Jan 6 20:22:01, load: 0.03, disk_r: 0 KB, disk_w: 0 KB + + value ------------- Distribution ------------- count + < 0 | 0 + 0 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1000 + 1 | 0 + + ^C + +The iopending tool samples at 1000 Hz, and prints a distribution of how many +disk events were "pending" completion. In the above example the disks are +quiet - for all the samples there are zero disk events pending. + + + +Now iopending is run with no arguments. It will default to an interval of 5 +seconds, + + # iopending + Tracing... Please wait. + 2006 Jan 6 19:15:41, load: 0.03, disk_r: 3599 KB, disk_w: 0 KB + + value ------------- Distribution ------------- count + < 0 | 0 + 0 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 4450 + 1 |@@@ 390 + 2 |@ 80 + 3 | 40 + 4 | 20 + 5 | 30 + 6 | 0 + + ^C + +In the above output there was a little disk activity. For 390 samples there +was 1 I/O event pending; for 80 samples there was 2, and so on. + + + + +In the following example iopending is run during heavy disk activity. We +print output every 10 seconds, + + # iopending 10 + Tracing... Please wait. + 2006 Jan 6 20:58:07, load: 0.03, disk_r: 25172 KB, disk_w: 33321 KB + + value ------------- Distribution ------------- count + < 0 | 0 + 0 |@@@@@@@@@ 2160 + 1 |@@@@@@@@@@@@@@@@@@@@@@@@@@@ 6720 + 2 |@@@@ 1000 + 3 | 50 + 4 | 30 + 5 | 20 + 6 | 10 + 7 | 10 + 8 | 10 + 9 | 0 + + 2006 Jan 6 20:58:17, load: 0.05, disk_r: 8409 KB, disk_w: 12449 KB + + value ------------- Distribution ------------- count + < 0 | 0 + 0 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 7260 + 1 |@@@@@@@ 1700 + 2 |@ 300 + 3 | 0 + 4 | 10 + 5 | 10 + 6 | 10 + 7 | 20 + 8 | 0 + 9 | 0 + 10 | 0 + 11 | 0 + 12 | 0 + 13 | 0 + 14 | 0 + 15 | 0 + 16 | 0 + 17 | 10 + 18 | 20 + 19 | 0 + 20 | 0 + 21 | 0 + 22 | 0 + 23 | 0 + 24 | 0 + 25 | 0 + 26 | 0 + 27 | 0 + 28 | 0 + 29 | 0 + 30 | 0 + 31 | 10 + >= 32 |@@@ 650 + + ^C + +In the first output, most of the time (67%) there was 1 event pending, +and for a short time there were 8 events pending. In the second output we +see many samples were off the scale - 650 samples at 32 or more pending +events. For this sample I had typed "sync" in another window, which +queued many disk events immediately which were eventually completed. + |
