[mythtv-users] 0.25 lookup metadata as part of jobqueue?
Raymond Wagner
raymond at wagnerrp.com
Sun Mar 11 15:43:16 UTC 2012
On 3/11/2012 08:03, Scott & Nicole Harris wrote:
> It would also be nice to set a different max jobs per job type. i.e. Allow
> 4 commercial flag jobs but only 1 transcode job at a time.
That's still far from optimal. Commercial detection can run in realtime
behind a recording, or at full speed behind a recording. At full speed,
it will fairly efficiency balance over two cores, meaning those four
jobs would saturate a dual socket, quad core server. In realtime, all
of those commercial detection runs will sit idle for the first ten
minutes, waiting for enough data to do icon detection, and then catch up
as fast as they can to the in-progress recording, again saturating that
high end server. Depending on how many simultaneous recordings you
have, you may not have a choice of which mode the jobs are going to run in.
With transcoding, you can either do a CPU intensive transcode, or a disk
intensive lossless transcode. Mythtranscode itself is primarily single
threaded due to its available codecs, so you would want to run one job
for each core when operating lossily. On the other hand, you would want
to run one job per available disk, and avoid conflicts with in-progress
recordings, when operating losslessly.
Then you get into issues with how do you mix multiple types of jobs.
Would you allow four commercial detection jobs and one transcoding job
to run at the same time? Do different types of jobs block each other?
Do you have some sort of sliding ratio between the two? You start
adding options for manual tuning of that behavior and suddenly you have
a giant, unwieldy transform table that most people don't know about and
no one actually wants to touch. See the weighting options available in
the disk scheduler as a prime example of this. Any usable change from
the current behavior would be to implement some form of heuristic
scheduler, that tracked what kind of resources were likely to be used
for different tasks against different types of recordings, and adjusted
accordingly.
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