On Wed, Mar 29, 2000 at 02:26:16PM -0500, John Regehr wrote:
> I'm not sure I see your point here. Seems like there are two choices that
> are compatible with low dispatch latency:
>
> 1) Eliminate all copies.
> 2) Sometimes wake up a thread during a copy.
It's the additional context switches and _added_ cache clears that bother
me. I'm thinking about it though.
The key issues are that: core kernel performance should not be harmed
for low latency and rescheds should not take the place of design for
low latency.
> How low does dispatch latency actually need to be? I was under the
> impression that small millisecond latency is good enough for an awful lot
Couple of milliseconds would be very solid and would be useful for many
applications using RTLinux as well as non-RTLinux multimedia, but
my personal feeling is that if we have to increase latency to make
Oracle or gcc or a file system run faster, then the latency should
be sacrificed.
> of applications. If we made a histogram by putting RTLinux and
> lowlatency-Linux applications into bins based on the worst dispatch
> latency they could reasonably tolerate, what would it look like?
RTLinux gets low microsecond worst case latencies.
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