[mythtv-users] Experimenting with TFW_DEF_BUF_SIZE to minimize HDTV IOBOUND errors

Yeechang Lee ylee at pobox.com
Sun Feb 19 16:04:19 UTC 2006

Mudit Wahal <mwahal at gmail.com> says:
> Seems like this issue is more common with HD sources as the demand for
> IO increases by a factor 5 vs SD. Adding multiple HD sources, compound
> the issue.
> Surprisingly, very few people see this issue.

Yes. Plus our mutual impresison that . . .

> I think there are more instances but no one is looking into their
> log files and take the *glitches* as part of HD.

I've had the exact same thought, having intensively searched the list
archives for references. I've been cautious/paranoid since the very
beginning of my MythTV days to always keep 'nice -n 19 tail -f
/var/log/mythtv/mythbackend' running somewhere--heck, I can flip to it
with two presses of a remote button in my current ratpoison setup--and
so I've always been aware of it.
> I think the devs can provide a menu/config option for these 3
> variables with big disclaimer.

That's my hope, too; to be honest I'm a little surprised there *isn't*
already such settings given just how configurable MythTV is in

> I only modified the first to 64mb and I'm very happy with results.
> Whenever I upgrade to 0.19, I've to do the same.

I've gotten the whole rewriting the .cpp file and generating a new
binary RPM down to a routine, but it still takes about a half hour
each time. I think the next time I am going to try keeping the minimum
the same absolute number as the default (in other words, adjust it
according based on what I've set the initial constant to) and fiddle
with the relative values of the others.

Yeechang Lee <ylee at pobox.com> | +1 650 776 7763 | San Francisco CA US

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