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TestServer

Notes and results on testing/troubleshooting the new (2009) LyX server.

1.  Scripts

1.1  timed-du.sh

Executes du /home/chr/www-user and times the execution, reporting execution times larger than a threshold.

1.2  timed-sleep.sh

Example: Running the script timed-sleep.sh as follows:

runs the command 'sleep 0.5' 1000 times, reporting when it takes longer then 510 ms to execute the command. With a good scheduler in the system, it should rarely take much more than 500 ms to execute the command.

• timed-sleep.sh

Summary of run sequence 1 for timed-sleep.sh 1000 0.5 515

Summary of run sequence 2 for timed-sleep.sh 10000 0.1 120

Run 1 -- on LyX server

• timed-sleep_2009-04-11.log

Important to note are the following data points.

• Data log was reinterpreted for a threshold of 515 ms to better compare with other runs.
• There were over 40 overruns in total, i.e. command 'sleep 0.5' took longer than 515 ms to execute during 40 of a 1000 runs.
• Most overruns were minor, i.e. 'sleep 0.5' took between 516..600 ms to execute.
• 5 overruns were intermediate, i.e. 'sleep 0.5' took between 600-706 ms to execute.
• 1 overrun was large, i.e. 'sleep 0.5' took 1317 ms!

It's my guess that there is something strange going on when 1/1000 executions of 'sleep 0.5' takes over a second to actually perform. However, the script in question should be tested on other Linux machines to check that such overruns typically don't occur.

Run ? -- on VM on Christian's home server

Note that the threshold was set to 515 ms instead of 500 ms.

• Only three overruns in total

chr@chr-desktop-i386:~$ ./timed-sleep.sh 1000 0.5 515
Overrun   1/1      of 'du' (524 ms > 515 ms)
Overrun   2/177    of 'du' (531 ms > 515 ms)
Overrun   3/514    of 'du' (516 ms > 515 ms)
# overruns = 3 / 1000

Run ? -- on Christian's home server

Running the test on the bare hardware results in hardly any overruns. Note that the test was evaluated with a threshold of 515 ms, resulting in only a single overrun.

chr@chr-pvr:~$ ./timed-sleep.sh 1000 0.5 515
Overrun   1/842    of 'du' (517 ms > 510 ms)
# overruns = 1 / 1000

Run ? -- on Christian's old PVR (mini-ITX)

Running the test on an old computer (mini-ITX, VIA cpu) to see what that produces.

• Only two overruns

chr@mythtv:~$ ./timed-sleep.sh 1000 0.5 515
Overrun   1/1      of 'du' (522 ms > 510 ms)
Overrun   2/153    of 'du' (516 ms > 510 ms)
# overruns = 2 / 1000

Run B? -- on Christian's home server

Ran the following command

and got

• 24 overruns out of 10000 sleep commands
• Maximum execution time was 145 ms.

Run B? -- on Christian's Mini-ITX

Ran the following command

and got

• 2 overruns out of 10000 sleep commands
• Maximum execution time was 174 ms.

Run B? -- on VM in Christian's home server

Ran the following command

and got

• 32 overruns out of 10000 sleep commands
• Maximum execution time was 158 ms.

Run B? -- on LyX server

Ran the following command

and got

• 517 overruns out of 10000 sleep commands
• Maximum execution time was over 2600 ms.

The output of the run is stored in the following file

• timed-sleep_2009-04-11_2.log

2.  Categories

• Development