[mythtv-users] Re:can we all get together and figure out cpu usage - Please respond

[Edward Wildgoose]

> Well I guess no one cares enough to actually do what I asked an post cpu
> usage. Instead you all seem to post sill suggestions that I have already
> tried

I appreciate your frustration, however, the "problem" with email lists is
that they are faceless and it can be doubly frustrating when you get little
response.  Often this just means that no one has the slightest clue how to
help you though!  (or they are on an easter holiday...)

I am happy to post my CPU idle info but you will have to wait until tomorrow
UK time for the details.  I also have a dual CPU 1 Ghz machine which makes
comparison difficult though!

One thing I have observed is something similar to your problem, but less
extreme.  It's something like someone else posting specs which seem much
faster than mine with similar (in theory) hardware.  I have decided that it
is often chipset issues and other subtle stuff which can make a big
difference.  For example I am never ever going to buy a motherboard with a
via chipset again - they appear to be extremely slow for lots of stuff, yet
the sticker speed is supposed to be fast.  They also crash in wierd ways
that no one else can help me debug, and for various unexplained reasons,
even by Alan Cox (who write me a nice note) is why USB stops working with
certain kernel versions....

Your problem is more extreme, but you did note that overclocking the bus
made a big difference.  To *me* this would suggest that you have a hardware
bottleneck somewhere.  I don't know why mplayer would not expose this, but
mythtv would...?  Possibly more efficient algorithms in mplayer than the
nuvplayer code...?  Also the de-interlace code or similar could be thrashing
the memory bus (have you tried disabling de-interlace and switching off
sound recording to isolate just the video decoder?)

Someone posted a research paper recently that you could decode HDTV in less
than 1Ghz of CPU by re-order the decode order so that there were more cache
hits and the memory bus took less of a hit!  The point is that for video you
can get BIG speed improvements or equally a machine like mine (and perhaps
yours) with a poor memory bus can take a disproportionate hit if the
algorithm is less "efficient".

ANyway, some ideas.  I think you need to get more extreme with your
debugging.  Can you squeeze in a full video card (take the case off?),
something like a cheap Geforce 2 just for debugging?  If performance rockets
at least you can isolate that one component...  Also see if you have any
interrupt collisions and fiddle with ACPI these can drain bus bandwidth.

Sorry, no magic bullet, but like most people here I really dont know how to
help.  Good luck though!