[mythtv-users] myth hangs + locks whole system [RAM OK]

[Ross Boylan]

On Fri, Aug 24, 2012 at 12:42 PM, Joseph Fry <joe at thefrys.com> wrote:

>
> On Fri, Aug 24, 2012 at 3:31 PM, Ross Boylan <
> rossboylan at stanfordalumni.org> wrote:
>
>> I attempted to ssh in, but did not get a connection until the system got
>> itself unstuck. (for both hangs).
>
>
> Ahh... so the system isn't truely hung... it eventually recovers.
>
Yes.  Though it takes about 15 minutes.

>
> There was a lot of discussion recently regarding the leap-second bug
> causing extremely high CPU utilization.  Doubt that's it, but it's possible
> I suppose.
>
I've rebooted since experiencing the hangs; my understanding is that will
take care of the leap second bug.  Also, I was experiencing similar
problems with 0.24.2 before the leap second.

>
> Either way, something is thrashing your system... and swapping is a
> likely candidate.
>
> Try copying some files around and see what kind of impact it has on the
> CPU... perhaps your not using DMA or something silly like that.
>
I regularly rsync large files.  It has some impact on performance and
responsiveness, but nothing like what I saw with the problem reported
earlier. The copy doesn't spike the CPU, which I think it might if it
didn't use DMA.

>
> I wouldn't think so, but perhaps there is some overhead associated with
> using the chroot?
>
> Anyway, nothing that mythtv is doing should push your system load to 60!
>  I suspect you had some major iowait going on.
>
Before the first failure (while watching a video, as opposed to the second
failure apparently from transcoding) there were lots of delays and
stutters, and lots of complaints from the front end about things taking too
long (sorry, don't have the messages available any more).

The system is heavily loaded and uses a fair amount of swap.  Maybe the
swapping is slowing IO responses, and things kind of cascade from there...
Ross
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