[mythtv-users] Mythbackend recording glitches
Greg Oliver
oliver.greg at gmail.com
Fri Oct 19 00:48:47 UTC 2018
On Thu, Oct 18, 2018 at 7:06 PM Allen Edwards <allen.p.edwards at gmail.com>
wrote:
> On Thu, Oct 18, 2018 at 3:59 PM Greg Oliver <oliver.greg at gmail.com> wrote:
>
>> On Thu, Oct 18, 2018 at 5:14 PM Allen Edwards <allen.p.edwards at gmail.com>
>> wrote:
>>
>>> On Thu, Oct 18, 2018 at 2:22 PM Allen Edwards <allen.p.edwards at gmail.com>
>>> wrote:
>>>
>>>>
>>>>
>>>> On Thu, Oct 18, 2018 at 1:41 PM faginbagin <mythtv at hbuus.com> wrote:
>>>>
>>>>> On 10/17/2018 9:53 PM, Stephen Worthington wrote:
>>>>>
>>>>> <snip>
>>>>>
>>>>> > But you really do need to change to using the 64-bit version. As of
>>>>> > 18.04, Ubuntu no longer supports the i386 version, and for a number
>>>>> of
>>>>> > versions before that the support has not been good - the i386
>>>>> versions
>>>>> > tend to have problems. And MythTV has not been tested much on i386
>>>>> > versions for a long time.
>>>>>
>>>>> While I agree with Stephen that Allen should change to a 64-bit version
>>>>> of Ubuntu, I have to say Ubuntu still supports 32-bit CPUs. They have
>>>>> dropped support for CPUs that don't support Physical Address Extension
>>>>> (PAE), but 32 bit CPUs manufactured since around 2004 do support PAE.
>>>>> _______________________________________________
>>>>>
>>>>
>>>> Some new information. I did a recording with mythfrontend off and it
>>>> had glitches. So that didn't work.
>>>>
>>>> I also think I might have figured out why my beloved Mythbuntu 8 was
>>>> not working. I said that it died because of a disk failure but what I
>>>> didn't say was that it was the second disk, one that was just for
>>>> additional storage. What occured to me today was that I probably needed to
>>>> just delete the reference to that now missing storage. I ran mythbackend
>>>> setup as part of documenting the settings and noticed that the second
>>>> storage location was not there and then I saved the settings. I am
>>>> thinking that might fix my Mythbuntu 8 system. Then I can chalk up the
>>>> multitude of hours I spent trying to get Mythbuntu 16 to work to
>>>> "entertainment".
>>>>
>>>> Just for a point of comparison to document the "progress" that myth as
>>>> made in the last 10 years. I reinstalled the 6200 video card and the old HD
>>>> and there is no ripping like there was with Mythbuntu 16 with that card and
>>>> no glitches. I am, as I have said, perfectly happy with the performance of
>>>> Mythbuntu 8 so if this proves to actually be stable, I may just quit here.
>>>> I am recording and watching at the same time in "top" below and there is no
>>>> swap used. I notice that the buffers space is much smaller and I may have
>>>> increased the buffers on the new setup at some point in the debugging stage
>>>> but in any event it is of interest.
>>>>
>>>> But I have a 1T HD coming today so I have to decide which OS I am going
>>>> to put on it...
>>>>
>>>> Allen
>>>>
>>>> top - 13:52:35 up 10 min, 2 users, load average: 0.34, 0.31, 0.24
>>>> Tasks: 131 total, 1 running, 130 sleeping, 0 stopped, 0 zombie
>>>> Cpu(s): 12.5%us, 1.4%sy, 0.0%ni, 85.0%id, 0.3%wa, 0.0%hi, 0.8%si,
>>>> 0.0%st
>>>> Mem: 2075424k total, 1433176k used, 642248k free, 27556k buffers
>>>> Swap: 6072528k total, 0k used, 6072528k free, 980256k cached
>>>>
>>>> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
>>>> 6803 dad 20 0 306m 153m 71m S 14 7.6 0:13.38
>>>> mythfrontend.re
>>>> 6393 root 20 0 146m 121m 50m S 2 6.0 0:05.58 Xorg
>>>> 6026 mythtv 20 0 306m 45m 11m S 0 2.2 0:12.48 mythbackend
>>>> 1 root 20 0 2844 1692 544 S 0 0.1 0:01.06 init
>>>> 2 root 15 -5 0 0 0 S 0 0.0 0:00.00 kthreadd
>>>> 3 root RT -5 0 0 0 S 0 0.0 0:00.00 migration/0
>>>> 4 root 15 -5 0 0 0 S 0 0.0 0:00.00 ksoftirqd/0
>>>> 5 root RT -5 0 0 0 S 0 0.0 0:00.00 watchdog/0
>>>> 6 root RT -5 0 0 0 S 0 0.0 0:00.00 migration/1
>>>>
>>>>
>>> So what is up with the swap? Looking at the screen capture for swapping
>>> and the theory that it is swap that is causing the glitches, why is there
>>> any swapping? There isn't any with mythbuntu 8 and there doesn't seem to be
>>> a need in 16 except to clear memory for buffer/cache. WTF?
>>>
>>> KiB Mem : 2061948 total, 135672 free, 450240 used, 1476036
>>> buff/cache
>>> KiB Swap: 2094076 total, 1704088 free, 389988 used. 1349872 avail
>>> Mem
>>>
>>> That says that memory used is 840M or less than half the RAM I have.
>>> But this buffer/cache is almost 1.5G. forcing about 400M to swap.
>>>
>>> So before I go buy more memory that I don't need, how can I limit the
>>> swapping? Google is not too helpful, something about you can't do this and
>>> everyone complains about it.
>>>
>>> Allen
>>>
>>> buffer/cache are not "used" - just what it says - buffer / cache. If
>> your system has swap in use, then at some point, it *did* need to use
>> swap. buffer/cache will be regained before swap is used otherwise. Try
>> taking swap out of your fstab and see what happens..
>>
>> The difference in OS between those versions you mentioned is not
>> minimal. Hardware requirements change significantly over time, and 2GB is
>> definitely not enought for any modern x86_64 kernel (running a full GUI).
>> You could get away with something that does not run a full window manager
>> and desktop probably. I run xorg and ratpoison which I think is about as
>> minimal as you can get. I must admit I am using an older i7 with 8 threads
>> and 16GB ram, but still.. I use this machine for a lot of non gui stuff -
>> only mythfrontend needs a gui...
>>
>> I use systemd to autologin me in to a tty, which my bash profile runs
>> startx and my .xinitrc starts ratpoison, and my .ratpoisonrc starts
>> mythfrontend..
>>
>> You could probably get away with that in 2MB..
>>
>> -Greg
>>
>
> Can anyone say that if I go to 4G or ram with the AMD 5400 that I will not
> run into some other limitation? I feel I grossly underestimated the effort
> and overestimated the benefit of upgrading to Mythbuntu 16.
>
> Perhaps I just need to figure out how to move everything from my 500G
> drive to my new about to be delivered 1T drive.
>
> Allen
>
I'm not going to lie - I keep replying to your threads because i admire
your commitment to getting things to work based on years old tech. The
linux kernel should accommodate that if it is specially built (cutting all
overhead, etc..), but of course a distro kernel will not get that done.
My last email stated how I ran mythfrontend (on my backend) in a minimalist
config - I would try something similar before buying hardware..
1. autologin on getty
[root at backend-0 systemd]# cat
/etc/systemd/system/getty at tty1.service.d/override.conf
[Service]
ExecStart=
ExecStart=-/sbin/agetty -a greg %I 38400
2. bash_profile
[root at backend-0 systemd]# cat ~greg/.bash_profile
# .bash_profile
# Get the aliases and functions
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi
# User specific environment and startup programs
PATH=$PATH:$HOME/.local/bin:$HOME/bin
export PATH
if [[ -z $DISPLAY ]] && [[ $(tty) = /dev/tty1 ]]; then
exec startx
fi
3. .xinitrc
[root at backend-0 greg]# pwd ; cat .xinitrc
/home/greg
# The black/white grid as background doesn't suit my taste.
xsetroot -solid black &
# Ratpoison is compatible with xcompmgr! now you can have real transparency
#xcompmgr -c -f -D 5 &
#fire up ratpoison!
exec /usr/bin/ratpoison
4. ratpoison
[root at backend-0 greg]# pwd ; cat .ratpoisonrc
/home/greg
exec xset -dpms
exec xset s off
exec vncserver -geometry 1800x1200 &
exec /home/greg/startMythfrontend.sh
(I use vnc and my own mythfrontend start up script:
[root at backend-0 greg]# cat startMythfrontend.sh
#!/bin/bash
while true ; do
if [ -f "$rf" ]; then
mythfrontend -v none >/dev/null 2>&1
sleep 2
fi
done
>From what I have followed for weeks, should be fairly straight forward for
you :) I really do not think you will get a more minimal resource usage
config working for your 2GB usage. I used to have a slave backend on a gen
1 ION which had 2GB ram (with .5GB used for GPU/VDPAU), and it did not have
enough oomph for (back then) fedora 19 (i believe), so I gave up on them..
It's just a sign of the times.. If you are happy with some old OS and some
old version of mythTV, then so be it.. I am not one to dictate anything.
Just sharing my experiences..
Hope you find something useful - I consider this a lot of typing - Stephen
Worthington on the other hand - his amount of detail and effort - you
should pay a month's water bill for his time :)
-Greg
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