Subject: Re: [linux-audio-dev] ALSA vs OSS/free
From: Jussi Laako (jussi.laako_AT_kolumbus.fi)
Date: Sun Mar 10 2002 - 16:03:30 EET
Ivica Bukvic wrote:
>
> am all for it. But one thing I do not comprehend is why is the
> user-space driver better than the kernel space one?
It's safer for the kernel. Also drivers would become more like applications
and less like something static in kernel.
Kernel modules are halfway there.
> Is it because this way kernel will eventually become more stable and
> more compact having all drivers loaded outside of the kernel space? (I'd
Yes, and drivers could do more complex things and use more kernel services.
Like using filesystems and directly reading configuration data from some
file.
> Also, in which case do you get better latency and overall system
> performance (I thought that if something is run in kernel-space that it
It will make latency and performance worse. Do doubt about that. It's all
about having minimal impact. So drivers should (IMO) run SCHED_FIFO and
never pre-empted as pre-emption destroys much of the effectiveness of SIMD
stuff and does bad things for cache also.
> Finally, is this because Linus wants to eventually get to the point
> where kernel won't require any more alterations, and where all the
> external modules will be developed and/or loaded as needed? (Again, I'd
I believe there is need to stop the kernel bloat with large number of
drivers and it's easier for driver developers not to be forced to sync with
kernel release cycle.
- Jussi Laako
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