Re: Real-time rw-locks (Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-15)

[Lee Revell <rlrevell@joe-job.com>]

On Mon, 2004-12-27 at 13:06 -0800, Bill Huey wrote:
> I was just having a discussion about this last night with a friend
> of mine and I'm going to pose this question to you and others.
> 
> Is a real-time enabled kernel still relevant for high performance
> video even with GPUs being as fast as they are these days ?
>
> The context that I'm working with is that I was told (been out of
> gaming for a long time now) that GPus are so fast these days that
> shortage of frame rate isn't a problem any more. An RTOS would be
> able to deliver a data/instructions to the GPU under a much tighter
> time period and could delivery better, more consistent frame rates.
> 
> Does this assertion still apply or not ? why ? (for either answer)

Yes, an RTOS certainly helps.  Otherwise you cannot guarantee a minimum
frame rate - if a long running disk ISR fires then you are screwed,
because jsut as with low latency audio you have a SCHED_FIFO userspace
process that is feeding data to the GPU at a constant rate.  Its a worse
problem with audio because you absolutely cannot drop a frame or you
will hear it.  With video it's likely to be imperceptible.

Lee