[mythtv-users] Help create synthetic mythtv I/O load using fio

[Boleslaw Ciesielski]

The idea of creating a synthetic mythtv load using fio has been floated 
previously by Jens Axboe (fio author; see 
http://www.gossamer-threads.com/lists/mythtv/users/212767#212767) but I 
haven't seen any followups after that.

So I tried to come up with a sample fio config but need someone to 
verify my assumptions and/or answer some questions. A first attempt is 
attached. Any comments or contributions are appreciated.

1. Someone said that myth fsyncs the file during recording once per 
second. Is this true?

2. What is the block size that myth uses when reading and writing streams?

3. Are there any special flags (e.g. O_DIRECT, O_SYNC) that myth uses 
for writes?

4. What would be a reasonable setting for ratemin to verify that system 
is capable of sustained minimal rate? Does that even make sense?

5. So far only recording and playback are simulated. If someone would 
come up with [mysql] and/or [mythcommflag] sections it would be great! I 
suspect mysql is a whole can of worms. mythcommflag should not be too 
bad though.

BTW, the whole reason I got into this was because of the infamous 
Seagate 1.5TB firmware problems. I am having performance problems with 
this drive even after applying the firmware upgrade. However, I cannot 
reproduce the problem outside of myth (the symptom is playback freezing 
for few seconds every couple of minutes or so). Yet I am convinced this 
is  hardware issue as it does not happen on any other drive. So I 
thought maybe creating this synthetic load would help.

However, I do think this maybe of more general usefulness for e.g. 
evaluating system capability. So, please do not hijack this thread into 
another Seagate discussion :-)

Bolek
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