[mythtv-users] backends without tuners (was Re: Transcoding is being done on frontends, not backend)

[Michael T. Dean]

On 01/08/2009 11:05 PM, Craig Sanders wrote:
> On Thu, Jan 08, 2009 at 03:47:03PM -0800, Brad DerManouelian wrote:
>   
>> The supported method of running jobs on other machines that do not  
>> have tuners is to run mythjobqueue.
>>     
...
> the only mention of mythjobqueue in the manual is a few paragraphs at
> section 23.25 - there's no mention anywhere in the manual that tunerless
> backends are unsupported, or that mythjobqueue should be used instead of
> mythbackend if no tuners are installed.

Note that if you run mythbackend on a host without any configured 
capture cards, all the parts of mythbackend that are not included in 
mythjobqueue are disabled--meaning you're basically running mythjobqueue 
+ cruft.  "What cruft?" you may ask.

# pmap -d `pidof mythbackend`
1683:   mythbackend -d -l /home/mythtv/log/mythtv.log
...
mapped: 335940K    writeable/private: 287712K    shared: 0K


# pmap -d `pidof mythjobqueue`
1702:   /usr/local/bin/mythjobqueue
...
mapped: 144584K    writeable/private: 35284K    shared: 0K

So that's 252428KiB of cruft (287712K - 35284K).  (Using 
writeable/private as mapped includes shared libraries like the MythTV 
libs (and many others) that are already in use by other apps--such as 
mythfrontend.)

Yeah, I realize that 256MiB of RAM isn't too expensive today, but why 
fill it up with garbage you're not using?  Why not use it for something 
useful, like the kernel buffers/cache--or preventing mythtranscode or 
mythcommflag from hitting swap or ...

And, as Brad has mentioned, since it was designed to be used that way, 
it's been tested that way.

Mike