Re: [xine-user] dvd playback smoothness under redhat

[Florin A. <fl...@an...>]

Quoting Miguel Freitas <mi...@ce...>:

> redhat says the rmap vm they use is great and it seemed quite the
> opposite to me: responsiveness looks much worse under rh kernel
> than
> stock kernels (2.4.17 or 2.4.19, for example). with rh kernel i
> experienced long delays when resuming swapped out apps and even
> hiccups
> with xmms that where gone from my system a long ago...

My experience is quite the opposite.

On servers, there is little doubt in my mind that the latest RH kernels
are a huge improvement. Running applications with lots of
threads/processes (MySQL, Apache) is much better on the new kernels;
looks like the context switches are performed a lot faster. Even
select() applications (Squid) seem to behave better.
However, we're not talking here about typical server workloads.

RMAP is not the only change. They also elevated the interrupt clock
frequency 5 times. As a direct result of that, now i can transcode from
VOB to DivX and my system continues to feel snappy and fast.
Under the older kernels, using transcode (or any other
multi-thread/process CPU hog) made my desktop difficult to use (sluggish
mouse, lazy apps, etc), despite the fact that the CPU is fairly powerful
(AthlonXP 1800+).

I'm using Xine and XMMS to play all kind of media content, including
DVDs, on the new RH kernels, and didn't had any problem whatsoever. If
anything, the performance seems to be better when the system is under
heavy load.

One thing you may have forgotten is the interrupt table. I forgot that too.
Basically, if you have overlapping interrupts (different devices sharing
the same interrupt), you'll notice performance penalties, or even
hiccups with multimedia applications under certain circumstances.
Make sure your interrupts are spread out evenly. This is a good advice
for using any media player, not just Xine.

By the way, anyone has any hints on spreading out the interrupts on an
MCI nForce motherboard? ;-) (using the embedded GeForce)

> to make things even worse hdparm couldn't enable dma on my dvdrom
> with
> rh kernel! 

Dude, c'mon, it's in the release notes...
Add this to your /etc/modules.conf:

options ide-cd dma=1

It's disabled by default because too many people complained about
problems with DMA on buggy CD-ROMs.

Overall, i was extremely impressed by the new kernels. I do regularly a
lot of "heavy-duty" :-) multimedia stuff, and with these kernels the CPU
hogs do not eat my entire CPU anymore; well, they still do it, but
somehow the other applications feel more responsive.
My feeling is that they focused mainly on the server side of things, but
anyway i saw a lot of improvement on my multimedia desktop too.

-- 
Florin Andrei

http://florin.myip.org/

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