Re: [Csnd-dev] Parallel Csound performance

This is odd, as I thought cspar was disabled in Csound?

On Wed, Oct 29, 2025 at 6:08 PM Victor Lazzarini
<[email protected]> wrote:
>
> I’m back investigating parallel Csound performance and it was interesting to see that
> Csound 7 is working well with it, in fact far better than 6.18.
>
> Running 1000 oscillator instrs for 60 secs I got these stats
>
> ksmps = 100
> -----------
> single thread: 3.9s
> 8 threads: 3.9s
>
> ksmps = 150
> ----------
> single thread: 3.5s
> 8 threads: 2.7s
>
> ksmps = 300
> ----------
> single thread: 3.2s
> 8 threads: 1.6s
>
> ksmps = 500
> ----------
> single thread: 3.2s
> 8 threads: 1.2s
>
> ksmps = 1000
> ----------
> single thread: 3.3s
> 8 threads: 0.8
>
> In comparison with 6.18 the last test ran at 11secs for 8 threads. In fact, 6.18 was always slower in parallel
> performance. Something was very broken there. Single-threaded performance is on a par with Csound 7.
>
> I can only think the new parser is working better with the parallel dispatch, or that something else was wrong
> in the 6.x and got fixed in 7. Anyway, I am pleased with these results. In general, ksmps=100 seems to be the break even
> point, below that multi-threaded performance is always losing. Also ksmps=1000 is more or less the highest gain,
> with diminishing returns after that. In my computer, 8 threads seem to be the optimal.
>
> best
> ========================
> Prof. Victor Lazzarini
> Maynooth University
> Ireland
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