On 06/25/2009 08:20 AM, Jon Smirl wrote: > On Thu, Jun 25, 2009 at 1:36 AM, Robert Hancock<hancockrwd@xxxxxxxxx> wrote: >> On 06/24/2009 10:26 PM, Jon Smirl wrote: >>> On Wed, Jun 24, 2009 at 5:11 PM, Takashi Iwai<tiwai@xxxxxxx> wrote: >>>>> The problem is knowing which sample in the background music to start >>>>> mixing the low latency laser blast into. >>>> That's why querying the accurate hwptr is important in PA. >>> I'm still not convinced that all of this logic should be exposed to >>> PA. Exposing these details is what makes ALSA hard to use. We should >>> be able to better isolate user space from this. If mixing were moved >>> into the kernel these details could be hidden. The in-kernel code >>> could then be customized for various sound DMA hardware. This would >>> also go a long ways toward getting rid of latency issues by removing >>> the need for real-time response from PA. >> Mixing really does not belong in the kernel. Moving it there doesn't remove >> any complication or problem, it just moves it to a different place where >> it's more difficult to program and less debuggable. Most OSes (Windows >> included) are moving in the direction of moving mixing out of the kernel, >> not into it. > > Mixing has a real-time component to it. Currently Desktop Linux > doesn't have real-time support. That's why pulse is developing > RealTimeKit. Buggy real-time code can easily lock your machine to > where you need to hit the reset button. > > User space code that is locked down with real-time priority and > servicing interrupts is effectively kernel code, it might as well be > in the kernel where it can get rid of the process overhead. > > http://git.0pointer.de/?p=rtkit.git;a=blob;f=README Just because it runs with real time priority does not mean it is effectively kernel code, or that it belongs there. Putting the code into the kernel adds a bunch of extra challenges for little reason, and also locks all users into a mixing scheme that may not meet their needs (ahem, Windows kernel mixer..) _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
