[mythtv] [PATCH] adjust filter update

[D Banerjee]

> I'm really sort of confused by the large CPU load this is causing - the
> difference is in the range of 1-3%CPU on my system.  It may be that the
code
> is less optimal on other architectures, which is what I was hoping this
> modification might correct, but it doesn't look like anybody has tried it
> yet.

I'm pretty sure it has to do with the amount of cache, and if you are
already using filters. If a frame is in L1/L2, it's a very low hit to run
another filter on it. So it may run fine, but any background app that causes
parts of a frame to be flushed from cache will hike up cpu usage greatly.

Also I've noticed mysterious cpu usage from cvs mythtv for some reason,
outside of filters. i.e. mythfrontend is taking 30% of cpu, where it used to
take nearly 0. Mythbackend when idle sometimes takes 50-60% cpu when
otherwise idle. So it may not even by the adjust filter.