[mythtv-users] How MANY backend threads!?!?!? ***** AUTO-REPLY *****

Steve Smith st3v3.sm1th at gmail.com
Thu Oct 14 07:55:12 UTC 2010

Ok so what horrendous high end task an i trying to do?
Spec. P3 900, 512mb , 1 pci dvbt, 1 Usb dvbt, 1 PVR150. Nvidia 5200
using xvmc.+bob. Ubuntu 10.0.4.  Combined fe+BE.
Task. Record 2 sd dvbt channels on 2 tuners, watch one.
Cpu at 30-40% peaking at 50% for BE process only.
BE has --noupnp & using mythbuntu .23 packages.
Why should the BE consume so much Cpu just dumping 2 mpeg streams to disk?
Is there anything else i can turn off to reduce the BE Cpu usage?
I upgraded from .21 not to get whizz bang features, but to get bug
fixes and stability for the BE. I am fully aware of the limitations of
my hardware.

On 10/14/10, Robert McNamara <robert.mcnamara at gmail.com> wrote:
> On Wed, Oct 13, 2010 at 3:40 PM, Brian Wood <beww at beww.org> wrote:
>> But, I would still like to know if 32 backend threads is normal or not,
>> and if so, what all those threads are doing to
>> enhance our Myth experience.
> Getting an accounting of what every threaded activity in the backend
> is explained to you is really a) asking for the impossible without
> knowing the configuration and b) would be silly anyway, since number
> of threads has *no* direct bearing on CPU use, as Gavin has explained,
> meaning c) it's unfair to ask that we account for the nitty gritty of
> the code if you're not willing to read the soruce yourself to see how
> it works.  Every recorder for each card is a thread.  Every time we
> write a file to the disk, that is done in a thread.  The uPnP/HTTP
> server will run in 5+ threads.  The backend will fork processes like
> mythfilldatabase into a thread.  This is just a portion of what the
> backend can and does do.  So, to speak very very broadly, 30+ threads
> is perfectly possible, and has no more bearing on the quantity of CPU
> used than it did at the beginning of this thread.
> It's frustrating when people suddenly show up demanding answers to
> questions that they themselves don't understand.  .23 is 2+ years
> newer than .21, and the backend has taken on lots more functionality.
> If people can't live with it taking a commensurate increase in
> resource use, they can and should remain at .21.  If you want to know
> what changed in those two years, it's reasonable that you have to seek
> those answers in the changelog.
> Robert
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