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--- ep:labs:05:contents:tasks:ex2 [2019/10/27 17:10]
emilian.radoi created
+++ ep:labs:05:contents:tasks:ex2 [2025/02/11 23:43] (current)
cezar.craciunoiu created
@@ Line 1: / Line 1: @@
-==== 02. [30p] Gnuplot bar graphs ====
+==== 02. [30p] iostat & iotop ====
-Use Gnuplot and the data from {{:ep:labs:ep_lab5_autodata.txt|autoData.txt}} to generate separate **bar** graphs for the following:
+=== [15p] Task A - Monitoring the behaviour with Iostat ===
-  * The "//MidPrice//" of all the "//small//" cars.
+<note tip>
-  * The average fuel consumption (MPG - miles per gallon) for all the "//large//" cars.
+Parameteres for iostat:
-  * The "//MaxPrice//" over the average fuel consumption for all "//chevrolet//" and "//ford//" cars.
+    * -x for extended statistics
+    * -d to display device stastistics only
+    * -m for displaying r/w in MB/s
+<code bash>
+$ iostat -xdm
+</code>
+Use iostat with -p for specific device statistics:
+<code bash>
+$ iostat -xdm -p sda
+</code>
+</note>
-The graphs should be as complete as possible (title, axes names, etc.)
+  * Run //iostat -x 1 5//.
+  * Considering the last two outputs provided by the previous command, calculate **the efficiency of IOPS** for each of them. Does the amount of data written per I/O **increase** or **decrease**?
-<note tip>
+Add in your archive screenshot or pictures of the operations and the result you obtained, also showing the output of iostat from which you took the values.
-**Hint:** Gnuplot conditional plotting.
+<note>
+How to do:
+  * Divide the kilobytes read (//rkB/s//) and written (//wkB/s//) per second by the reads per second (//r/s//) and the writes per second (//w/s//).
+  * If you happen to have quite a few [[https://en.wikipedia.org/wiki/Loop_device|loop devices]] in your **iostat** output, find out what they are exactly:
+<code bash>
+$ df -kh /dev/loop*
+</code>
 </note>
 <solution -hidden>
-<code>
+The way to calculate the efficiency of IOPS is to divide the reads per second //(r/s)// and writes per second //(w/s)// by the kilobytes read //(rkB/s)// and written //(wkB/s)// per second.
-with boxes - pentru bar chart (set style fill solid - sa fie pline)
+Example: the amount of data written per I/O for ///dev/sda// increases during each iteration:
-reset
+{{ :ep:labs:ep2017_l3_ex01.png?700 |}}
-set size 1, 1
+<code>
-set multiplot layout 2,2 rowsfirst
+/105 = 505KB per I/O
+/102 = 697KB per I/O
+</code>
-set title 'Graph Small Cars'
+If everything is zero in iostat - perform some I/O operations...
-set xlabel 'Car'
+</solution>
-set ylabel 'MidPrice'
-unset key
-plot "data5.txt" using (strcol(4) eq "small" ? $6 : 0) w l lw 0.5 lc rgb 'red'
-set title 'Graph Fuel Consumption'
-set xlabel 'Car'
-set ylabel 'Fuel'
-unset key
-plot "data5.txt" using (strcol(4) eq "large" ? ($8 + $9)/2 : 0) w l lw 0.5 lc rgb 'blue'
-set title 'Graph Avg'
+=== [15p] Task B - Monitoring the behaviour with Iotop ===
-set xlabel 'X'
+<note tip>
-set ylabel 'Y'
+**Iotop** is an utility similar to top command, that interfaces with the kernel to provide per-thread/process I/O usage statistics.
-unset key
-plot "data5.txt" using (strcol(2) eq 'chevrolet' || strcol(2) eq "ford" ? $7 : 0) w l lw 0.5 lc rgb 'green', \
+<code>
-     "data5.txt" using (strcol(2) eq 'chevrolet' || strcol(2) eq "ford" ? ($8 + $9)/2 : 0) w l lw 0.5 lc rgb 'orange'
+Debian/Ubuntu Linux install iotop
+$ sudo apt-get install iotop
-unset multiplot
+How to use iotop command
+$ sudo iotop OR $ iotop
 </code>
-</solution>
+Supported options by iotop command:
+| **Options** | **Description** ^^
+| --version | show program’s version number and exit ||
+| -h, --help	| show this help message and exit ||
+| -o, --only	| only show processes or threads actually doing I/O ||
+| -b, --batch	| non-interactive mode ||
+| -n NUM, --iter=NUM	| number of iterations before ending [infinite] ||
+| -d SEC, --delay=SEC	| delay between iterations [1 second] ||
+| -p PID, --pid=PID	| processes/threads to monitor [all] ||
+| -u USER, --user=USER	| users to monitor [all] ||
+| -P, --processes	| only show processes, not all threads ||
+| -a, --accumulated	| show accumulated I/O instead of bandwidth ||
+| -k, --kilobytes	| use kilobytes instead of a human friendly unit ||
+| -t, --time	| add a timestamp on each line (implies –batch) ||
+| -q, --quiet	| suppress some lines of header (implies –batch) ||
+</note>
+  * Run iotop (install it if you do not already have it) in a separate shell showing only processes or threads actually doing I/O.
+  * Inspect the script code ({{:ep:laboratoare:dummy.sh|dummy.sh}}) to see what it does.
+  * Monitor the behaviour of the system with iotop while running the script.
+  * Identify the PID and PPID of the process running the dummy script and kill the process using command line from another shell (sending SIGINT signal to both parent & child processes).
+  * Hint - [[https://superuser.com/questions/150117/how-to-get-parent-pid-of-a-given-process-in-gnu-linux-from-command-line|How to get parent PID of a given process in GNU/Linux from command line?]]
+Provide a screenshot in which it shows the iotop with only the active processes and one of them being the running script. Then another screenshot after you succeeded to kill it.
+<solution -hidden>
+{{:ep:laboratoare:lab3-ex4.png?600}}
+**dd** performs disk writes... wow! Reason why there are no disk reads is because it uses pseudo-files from **devtmpfs** that don't record these statistics. Also, **tmpfs** are not disks :p
+Find PPID from PID: ps -o ppid= -p PID
+Send SIGINT signal: kill -SIGINT PID,PPID
+</solution>

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ep/labs/05/contents/tasks/ex2.1572189045.txt.gz · Last modified: 2019/10/27 17:10 by emilian.radoi

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