Re: [Tvtime-devel] poor performance

[Billy B. <ve...@du...>]

kle...@gm... (kle...@gm...):

> Billy Biggs wrote:
> > 
> > Maybe you should email NVIDIA as well and get their opinion on this?
> > Can you think of anything you have done in the kernel to deserve
> > such poor performance?
> 
> I have found the problem, msp3400 does often output this kernel
> messages:

  How does this explain the bad performance with 'x11perf -shmput500'
which has nothing to do with your capture card?

> bttv0: skipped frame. no signal? high irq latency?
> i2c_adapter i2c-1: sendbytes: error - bailout.
> msp34xx: I/O error #1 (read 0x12/0x18)
> 
> Always when i2c_adapter errors are appearing, tvtime slows down a
> little bit.  Unloading msp3400 module solves this problem.

  We should post about this to video4linux-list and see what they say
about it, but something is broken, but I don't think it is here.  I
think something is causing DMA transfers on your machine to suck, and
it's something wrong elsewhere in the kernel.

> I cannot find such a problem with xawtv, zapping so i think tvtime is
> using a function(?) that doesn't work properly.

  xawtv and zapping usually use 'overlay' mode where the capture card
DMAs directly to video memory.  tvtime works by capturing to system
memory, processing the video, and uploading to your video card, which
leads to a lot more use of your system's resources.  I think there is
something fundamentally broken with your kernel that is hurting your
performance though, your x11perf numbers were too horrible.

  How about you post the full output of 'dmesg' to a webpage, and maybe
then see if it's something we should post to a kernel list ... ??

  -Billy