[mythtv-users] Recording Priority = 99 not a trump all?

Jason Ward jasonfward at gmail.com
Thu Jun 24 01:23:10 UTC 2010


On 24 June 2010 02:02, Thomas Mashos <tgm4883 at gmail.com> wrote:

> On Wed, Jun 23, 2010 at 5:19 PM, Jason Ward <jasonfward at gmail.com> wrote:
>
>>
>>
>> On 24 June 2010 01:06, Douglas Peale <Douglas_Peale at comcast.net> wrote:
>>
>>> On 06/23/2010 03:24 PM, Michael T. Dean wrote:
>>> > On 06/23/2010 06:05 PM, Jason Ward wrote:
>>> >> On 23 June 2010 22:55, Douglas Peale wrote:
>>> >>
>>> >>> On 06/23/2010 02:33 PM, David Engel wrote:
>>> >>>
>>> >>>> When SchedMoveHigher is enabled, the
>>> >>>> scheduler moves recordings around one at a time and the first fit
>>> >>>> wins.  it does not continue on looking for "better" fits.
>>> >>>>
>>> >>> The example I cite is a recording of NCIS on ION. I have 7 copies of
>>> >>> ION on
>>> >>> my system 1 OTA HD, 3 cable HD, and 3 cable SD. All
>>> >>> three cable SD channels had a priority of -10 the rest were priority
>>> 0.
>>> >>> There was nothing else scheduled at that time that would
>>> >>> match any of my recording criteria. No conflicts.
>>> >>>
>>> >>> So, you contend that in this situation for the scheduler to choose a
>>> SD
>>> >>> channel over an HD channel is not a bug?
>>> >>>
>>> >> Well David says the scheduler is written to find the first fit not the
>>> >> best
>>> >> fit,
>>> >
>>> > Well, more precisely, David said that when users have the setting I
>>> > mentioned way back in the 3rd post in this thread (
>>> > http://www.gossamer-threads.com/lists/mythtv/users/441014#441014 )
>>> > enabled, one of its effects is to disable best-fit scheduling and,
>>> > instead, use first-fit scheduling in some circumstances.
>>> >
>>> > In other words, the setting he meant by, "SchedMoveHigher," is
>>> actually,
>>> > "Reschedule higher priorities."
>>> >
>>> >>   so yes, there is no bug in so much as the scheduler has worked as it
>>> is
>>> >> designed to work.
>>> >
>>> > Exactly.  And, more importantly, as the user configured it to work.
>>> >
>>> >>    However, I would agree this isn't exactly desirable
>>> >> behavior,
>>> >
>>> > Which is why we have a setting that you can disable (in mythfrontend
>>> > settings, Utilities/Setup|Setup|TV Settings|Recording Priorities,
>>> > IIRC).  The default is that "Reschedule higher priorities" is enabled
>>> > because we got far more users complaining that MythTV wasn't recording
>>> > everything they wanted than users complaining that they don't get a
>>> show
>>> > they want until its second airing.
>>> >
>>> > Again, this is all explained very nicely in
>>> > http://www.mythtv.org/docs/mythtv-HOWTO-12.html .  Note, also--as I've
>>> > said /way/ too many times--anyone who modifies /any/ priority other
>>> than
>>> > recording rule priorities should read and understand that entire
>>> section
>>> > before doing so.  (And, after reading it, you'll likely see that you
>>> > don't want to modify other priorities.)
>>> >
>>> > Mike
>>>
>>>
>>> If I read those correctly, once the scheduler has decided that show X
>>> (say "NCIS") has the highest priority and should be
>>> scheduled next, it arbitrarily and randomly chooses a channel & tuner
>>> from those not currently scheduled for something else that
>>> is capable of receiving the particular show, completely ignoring channel
>>> priority and tuner priority.
>>>
>>
>> No.  You don't seem to be reading what more than one person including
>> David have said: Which is if you have YOURSELF selected the option to
>> reschedule higher priority items to make way for lower priority items that
>> would not otherwise be recorded, then one of the effects of YOUR SELECTION
>> is that the scheduler moves to first fit.  If you want best fit, then
>> disable the option to reschedule higher priority items which is the default.
>>
>> Jason
>>
>> _______________________________________________
>> mythtv-users mailing list
>> mythtv-users at mythtv.org
>> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>>
>>
> I'll throw my 2 cents in since I haven't fully understood how the scheduler
> works and it looks like past information is getting forgotten about.
>
> @Douglas
>
> I doubt it is randomly choosing a tuner to use. Likely it is selecting the
> first available tuner, which may be SD. As said before, do the "mythbackend
> -v
> schedule --testsched"
>
> @Jason
> IIRC, he said that with no other shows recording, and only one scheduled
> (NCIS), and that show being on 7 different channels at that time, that
> MythTV selected his SD channel over the HD ones. Without any conflicts
> (since there were 0 other shows recording), why did it choose SD?
>
>
> I've read elsewhere that you need to add the tuners in the backend in a
> specific order. I wonder if the scheduler is selecting tuner #1 (which the
> show is on) which happens to be a SD tuner and then doesn't try any others?
>

Maybe :) but what he said makes no difference in this case.  First fit
(which when you turn on the option to reschedule higher priority items)
means the scheduler doesn't bother to look for best fit, that it could have
chosen the HD channel is irrelevant to a first fit algorythm, because it
never even checks, it stop as soon as it hits the first fit.  There may or
may not be  be ways to ensure that the scheduler checks HD streams first
(others would need to advise on that) but still if *you* select to
reschedule higher priority items then the scheduler ALWAYS selects the first
fit it finds, not the best fit.  If you want it to choose best fit then turn
off the option to reschedule higher priority items.

I'm at a loss to understand why this is hard to understand.  I'm not sure
it's the best way for the scheduler to work, but it is how it works.
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