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

devsk funtoos at yahoo.com
Wed Dec 27 18:38:58 UTC 2006


Mark,

Did you file a bug yet? Filing a bug means that problem gets recorded and is searchable by others.

Are you running ~ARCH with gentoo or stable?

With dual core cpus, I have found that PREEMPT, SCHED_MC (multicore scheduler) and NUMA need to be off for stable operation. I only use Voluntary Kernel Preemption and Preempt the big kernel lock. And I have seen the strace magic happen on my machine before, so you are not alone....:-)

I have been running myth on X2 3800+ for a while in SMP configuration and load both cores all the time without any freezing or hangs. I have had stable operation with last of the 2.6.17, 2.6.18 and now 2.6.19.1; all gentoo-sources patched for reiser4 and suspend2. I run my gentoo with ~amd64.

-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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