[mythtv-users] Running mythcommflag on another PC?

Ian Evans dheianevans at gmail.com
Sun Mar 3 04:31:46 UTC 2024

On Sat, Mar 2, 2024 at 7:02 PM Stephen Worthington <stephen_agent at jsw.gen.nz>

> As for mythcommflag performance, for processors 10 years old or
> younger and not the super cheap variety, then they can normally do
> commflagging on one recording per CPU core/thread in real time.  So
> for a 4 core dual threaded CPU, you could do 8 mythcommflag processes
> simultaneously in real time as 8 recordings happen together.  The
> trick with real time commflagging is that it gets done in RAM, on the
> buffered recording data before it gets written to disk.  Once the data
> has been written to disk, reading it back again slows down
> commflagging, as there is then the problem of contention for the disk,
> with the heads having to move between recordings.  So you also need
> enough RAM, as well as the CPU resources.
> I gave up doing commflagging a long time ago as here in New Zealand,
> it never gave useful results.  So I have not tried commflagging with
> the current generations of CPU, which are much faster again than 10
> year old ones.  They may well be able to do more than one mythcommflag
> operation per CPU thread, maybe even three or four.
> I would recommend a starting position of one commflag operation per
> CPU core/thread being run on the main recording box, starting the
> commflagging when the recording starts.  Then just let any more
> simultaneous recordings that go over that limit have their
> commflagging queued to be done later.  There should not be any need to
> have another box doing commflagging unless you are recording 20 things
> at once all day.

Just a quick background. My wife and I are currently working on another
place and I've just MacGyver'd a temporary setup so we'd have a PVR and I
could tiner with v34.

The backend is currently running on an old Toshiba Satellite laptop. It has
8 gig of RAM and a i7-3720QM CPU.

According to Intel ARK:
- Total Cores 4
- Total Threads 8
- Max Turbo Frequency 3.60 GHz
- Intel® Turbo Boost Technology 2.0 Frequency‡ 3.60 GHz
- Processor Base Frequency 2.60 GHz
- Cache 6 MB Intel® Smart Cache

When I tried running commercial detection a few months ago, I remember the
load spiking to 2.00. Can't remember if I had that running post recording
while there were other recordings. I may have not set it for real-time
detection thinking a laptop couldn't handle it. I'll have to change the
setup when my the SVU marathon is over.
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