On Sun, Aug 24, 2014 at 9:26 AM, Paul Robert Marino <[log in to unmask]> wrote:
> That said I've run hundreds of mission critical systems many accurate to within 5
> milliseconds on the standard kernel with proper tuning and a stripped
> down OS install for nearly a decade and Ive never had an issue.

The standard Linux kernel shipped by most distributions is actually
quite effective in applications that require millisecond level
scheduling precision. Paul's experience confirms this.

If the need for smaller interrupt and scheduling latency arises, the
stock kernel source allows you to generate a soft real-time kernel by
choosing the "Preemptible Kernel" (PREEMPTDESKTOP) during kernel
configuration and compilation.

What the standard kernel source doesn't provide is reliable and
consistent sub-millisecond scheduling. Applying the PREEMPT_RT patch
generates what can for the most part be considered a hard RTOS kernel.

For the most part in 99% of applications the standard kernel will
suffice. Without knowing what Lee's application is, it is impossible
to determine if he really needs a soft or hard real-time kernel.

Brandon Vincent