On Sun, 26 Aug 2001, Julian Elischer wrote:
> Comparative times for 'make buildworld'
> for unmodified and KSE (milestone-2) kernels
>
> unmodified -current
> 2138.464u 3358.378s 1:37:39.77 93.8% 842+1080k 45105+176988io 3208pf+0w
> modified KSE kernel
> 2143.716u 3363.311s 1:37:50.33 93.8% 841+1081k 45435+176988io 3214pf+0w
>
> I'm very glad to see that the overhead added was not too great.
> (well within the margin of error I'm sure)
Since it is non-negative, why would anyone want it?
However, the benchmark seems to be flawed. Buildworld's system time should
be only about 20% of its user time. To pessimize it by a factor of 7.5,
you need to turn on lots of debugging options (which are on by default in
-current).
> More actual code will be needed to get away from 1:1, so this is just a
> baseline.
>
> the next steps are for us a s a groupt to decide if this is really the way we
> want to go,
> and if so, whether we want to commit these changes to make them available for
> the world
> to work on as a base for real threading support. The alternative is to
> do linux-type threading with processes (peter wemm has been investigating a
> variant
> on this scheme). This is probably a no-turning-back commit.
How much faster (or slower) will it be for threaded programs (for various
numbers of CPUs)? I don't see how it can be faster for a single CPU
(interrupt threads in the kernel show that using threads tends to pessimize
both efficiency and latency for a single CPU).
Bruce
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