comments on late joyrides re: rt performance

Daniel Drake dsd at laptop.org
Thu Aug 7 17:25:39 EDT 2008


Hi Victor,

Thanks a lot for the feedback.

On Thu, 2008-08-07 at 21:45 +0100, victor wrote:
> One of the things I have been playing with is a little MIDI file
> player
> (one of the test/example activities in
> devel.laptop.org/activities/csndsugui),
> which uses a soundfont synthesis engine. On the older system, I
> can play most files with only the occasional dropout, generally
> quite solidly. But on the later (2232 and 2263), I get many more
> dropouts

We are already aware of an audio performance regression and believe it
be related to 2 things:
 - hal polls our battery a lot more than it used to, even when fully 
   charged, and EC commands disable interrupts and cause sound stutters.
   (I'm working on fixing hal, I sent patches upstream)
 - the kernel upgrade from 2.6.22 to 2.6.25 also included some changes
   (which we haven't identified yet) which cause these problems.
   Downgrading to 2.6.22 restores the previous audio performance.

Thanks for pointing out your test-case though! So far we have been
reproducing these issues by using TamTamMini, TamTam is indeed
affected. :(

Here is the relevant ticket:
http://dev.laptop.org/ticket/7603
Contributions welcome! It is a tricky one.

Thanks,
Daniel




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