[mythtv-users] Update - FIXED mythbackend not responding -and even more weirdness

Wed Dec 27 22:25:01 UTC 2006

On 12/27/06, devsk <funtoos at yahoo.com> wrote:
>
>
> > I've gotten a little gun shy with some of the responses I've received back
> for filing reports
> > so now I'm far more careful.
>
> Yeah, I have seen bad responses as well. But its always like that. (In fact,
> the bug triagee on BGO hates me...I have had spats with him where he would
> just close the bug for no reason. But I still file bugs.)

OK - sorry for that but good to know I'm not the only guy getting hit
by stuff like that.

>
> > Do you mean problems for Myth or problems in general?
>
> Problems in general, and that includes myth. I could hang or reset the
> system if I loaded both the cores to 100% with many concurrent processes
> doing various things like encoding, doing IO, scrolling in firefox etc. My
> favorite was: you scroll in firefox while doing video encoding in bg, system
> resets....:-). Many times, it would reset resuming a vmware image or
> compiling a big package. Basically, anything that would load CPU, IO and
> network paths at the same time, would most certainly bring it down. I
> haven't seen those for a long time now.

We haven't seen many problems like you describe. Once in awhile my
wife (it's her desktop that serves as the Myth backend base don it's
location in the house, slots free, etc.) will have an app hang up but
I don't think the machine has ever spontaneously rebooted. The Myth
problems have been consistent though.

>
> > This P4HT has been SMP for a long time but the only issue has been
> mythbackend. It's
> > been an issue over all SMP kernels I've run since about 2.6.14.
>
> IMO, if  it is not a dual core, it doesn't make much sense to run SMP for HT
> only. I have turned HT off on my P4 in the other machine because it doesn't
> give me many benefits and its one more variable out of the instability
> equation i.e. I am fine with losing 10-15% best case scenario performance
> for stability. With dual core, its little different. By turning SMP off on a
> dual core, you are probably losing close to 50% performance in best case
> scenarios.

I don't have major problems turning it off. My wife doesn't drive the
machine very hard. The only thing that does come up, quite typically
right after 9PM and again after 10PM, is this scenario:

1) Myth backend is just fininshed recording two programs. We have two
Hauppage PVR cards using ivtv.

2) The two previous recordings are going through
mythcommflag/transcoding type processes so that adds CPU overhead.

3) My wife is sitting on that machine using Myth frontend watching
some other program.

4) I'm in another room watching some program on one of the Pundit-R
backends while my son is in the living room watching a 3rd program on
the second Pundit-R.

All of that loading typically happens right after 9PM or 10PM for
obvious reasons. The load goes up on the backend, but it's not at
100%. The machine acts fine. It's response, etc., but mythbackend
quits.

>
> Anyway, if you want to use SMP, try turning off settings (NUMA doesn't apply
> to intel HT or amd dual cores) that I mentioned. Leave SCHED_SMT out as well
> if you have it enabled (take more relevant code with little benefit out of
> the equation). Another recommendation I would make is to try the 2.6.19-r2
> gentoo-sources. There are so many ATA/IO related problems fixed in 2.6.18
> and particularly in 2.6.19, that its not even funny. I know the kernel
> upgrade pain, but I think 2.6.19-r2 is worth it.

I'll try to give some effort to each of your suggestions. They are a
bit of work as it requires messing with ivtv and sometimes that means
deleting all the old cards in mythsetup and redo-ing all the setups
again. None the less if it solves the problem it has to be done.

thanks,
Mark
>
> -devsk
>
>
> >
> > -devsk
> >
> >
> > ----- Original Message ----
> > From: Mark Knecht <markknecht at gmail.com>
> > To: hah at alumni.rice.edu; Discussion about mythtv <mythtv-users at mythtv.org>
> > Sent: Wednesday, December 27, 2006 9:37:05 AM
> > Subject: Re: [mythtv-users] **Update - FIXED** mythbackend not responding
> > -and even more weirdness
> >
> >
> > On 12/27/06, Henry A Harper III <hah at alumni.rice.edu> wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: mythtv-users-bounces at mythtv.org
> > > > [mailto:mythtv-users-bounces at mythtv.org]On Behalf Of Mark Knecht
> > > > Sent: Wednesday, December 27, 2006 9:48 AM
> > > > To: Discussion about mythtv
> > > > Cc: dusteur at excite.com
> > > > Subject: Re: [mythtv-users] **Update - FIXED** mythbackend not
> > > > responding -and even more weirdness
> > > >
> > > >
> > > > On 12/27/06, Bill Arlofski <waa-mythtv at revpol.com> wrote:
> > > > <SNIP>
> > > > >
> > > > > Does any of the burden of this problem fall on the mythtv devs? Is
> it
> > a
> > > > > programming issue with Mythtv and SMP? Is it an AMD Athlon64 X2 SMP
> > > > > issue specific to the CPU I am using? Again, I do not know.
> > > > >
> > > > <SNIP>
> > > >
> > > > Interesting results. It might well be SMP related. I have a P4HT
> > > > machine as the backend server and it's having similar problems.
> > > >
> > > > We are having a lot of problems with mythbackend just shutting off,
> > > > but it seems to only shut off only when there are mythfrontend
> > > > machines that are just finishing watching programs. Over the Christmas
> > > > break we travelled for 4 days. mythbackend recorded everything
> > > > correctly for about 40 hours of material. Lots to watch, so we started
> > > > trying to do so. Yesterday mythbackend shut off 3 times. I'd restart
> > > > the backend and it would happen again maybe 1-2 hours later.
> > > >
> > > > Thanks for the SMP idea. I'll look at that and report back.
> > > >
> > >
> > > FYI, my 4600+ x2 w/ 2.6.17 SMP kernel in a FE/BE has been up 97 days
> with
> > no
> > > backend "weirdness" other than xbox360-caused upnp issues (just 100%
> core
> > > usage, not unresponsive) until I went to newer svn head last week.
> >
> > Good to know and glad it's working for you. We're Gentoo here. HEre's
> > what's installed on the backend machine:
> >
> > dragonfly ~ # eix -Ic mythtv
> > [I] media-tv/mythtv (0.20_p11626): Homebrew PVR project
> > [I] x11-themes/mythtv-themes (0.20): A collection of themes for the
> > MythTV project.
> > Found 2 matches.
> > dragonfly ~ # uname -a
> > Linux dragonfly 2.6.17-gentoo-r2 #4 SMP PREEMPT Fri Nov 24 14:20:30
> > PST 2006 i686 Intel(R) Pentium(R) 4 CPU 3.00GHz GenuineIntel GNU/Linux
> > dragonfly ~ #
> >
> > Note that this problem existed before on myth-0.18 and 0.19. It was
> > not changed much by going to gcc-4.1.1. Pretty much the same level of
> > problems.
> >
> > Here's an example of something I'm seeing in the log files this
> > morning. I do NOT know if this is a reoccuring problem. It's jsut at
> > the end of my log:
> >
> > [mpeg2video @ 0xb7345348]00 motion_type at 0 27
> > [mpeg2video @ 0xb7345348]00 motion_type at 0 28
> > [mpeg2video @ 0xb7345348]00 motion_type at 0 29
> > [mpeg2video @ 0xb7345348]Warning MVs not available
> > *** glibc detected *** /usr/bin/mythbackend: double free or corruption
> > (fasttop): 0xa8605138 ***
> > ======= Backtrace: =========
> > /lib/libc.so.6[0xb5ea9bab]
> > /lib/libc.so.6(__libc_free+0x79)[0xb5eab0e7]
> >
> /usr/lib/gcc/i686-pc-linux-gnu/4.1.1/libstdc++.so.6(_ZdlPv+0x21)[0xb603a929]
> >
> /usr/lib/libmythtv-0.20.so.0(_ZNSt6vectorIiSaIiEE13_M_insert_auxEN9__gnu_cxx17__normal_iteratorIPiS1_EERKi+0xfc)[0xb78a1da6]
> > ======= Memory map: ========
> > 08048000-0812a000 r-xp 00000000 03:08 296515     /usr/bin/mythbackend
> > 0812a000-0812b000 rw-p 000e2000 03:08 296515     /usr/bin/mythbackend
> > 0812b000-083cc000 rw-p 0812b000 00:00 0          [heap]
> > a8400000-a8460000 rw-p a8400000 00:00 0
> > a8460000-a8500000 ---p a8460000 00:00 0
> > a8600000-a8644000 rw-p a8600000 00:00 0
> > a8644000-a8700000 ---p a8644000 00:00 0
> > a9000000-a9100000 rw-p a9000000 00:00 0
> > a91f4000-a91f5000 ---p a91f4000 00:00 0
> > a91f5000-a99f5000 rw-p a91f5000 00:00 0
> > a99f5000-a99f6000 ---p a99f5000 00:00 0
> >
> > <SNIP>
> > b7ef7000-b7ef8000 rw-p 00000000 03:08 705168
> > /usr/lib/mythtv/filters/libbobdeint.so
> > b7ef8000-b7efa000 r-xp 00000000 03:08 705149
> > /usr/lib/mythtv/filters/libadjust.so
> > b7efa000-b7efb000 rw-p 00001000 03:08 705149
> > /usr/lib/mythtv/filters/libadjust.so
> > b7efb000-b7f03000 r-xp 00000000 03:08 753706     /lib/libnss_files-2.4.so
> > b7f03000-b7f05000 rw-p 00007000 03:08 753706     /lib/libnss_files-2.4.so
> > b7f05000-b7f0e000 r-xp 00000000 03:08 522754
> > /usr/qt/3/plugins/sqldrivers/libqsqlmysql.so
> > b7f0e000-b7f0f000 rw-p 00009000 03:08 522754
> > /usr/qt/3/plugins/sqldrivers/libqsqlmysql.so
> > b7f0f000-b7f10000 rw-p b7f0f000 00:00 0
> > b7f10000-b7f29000 r-xp 00000000 03:08 753640     /lib/ld-2.4.so
> > b7f29000-b7f2a000 r--p 00019000 03:08 753640     /lib/ld-2.4.so
> > b7f2a000-b7f2b000 rw-p 0001a000 03:08 753640     /lib/ld-2.4.so
> > bf9cd000-bf9e3000 rw-p bf9cd000 00:00 0          [stack]
> > ffffe000-fffff000 ---p 00000000 00:00 0          [vdso]
> > 0: start_time: 0.036 duration: 151.976
> > 1: start_time: 0.026 duration: 151.954
> > stream: start_time: 0.289 duration: 1688.731 bitrate=5193 kb/s
> > [mpeg2video @ 0xb7345348]ac-tex damaged at 22 6
> > 0: start_time: 0.036 duration: 232.471
> > 1: start_time: 0.026 duration: 232.444
> > stream: start_time: 0.289 duration: 2583.125 bitrate=7217 kb/s
> > Starting up as the master server.
> >
> >
> > I don't even know if the Myth developers read this list or want this
> > info. Maybe pass it upstream through Gentoo?
> >
> > Thanks,
> > Mark
> > _______________________________________________
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[mythtv-users] **Update - FIXED** mythbackend not responding -and even more weirdness

[mythtv-users] Update - FIXED mythbackend not responding -and even more weirdness