Re: [Csnd-dev] [EXTERNAL] Re: [Csnd-dev] Parallel Csound performance

Victor Lazzarini <[email protected]> Wed, 29 Oct 2025 22:22:35 +0000
Newsgroups gmane.comp.audio.csound.devel
Message-ID <[email protected]>
No, I don't think we ever disabled it. There were some questions about re-enabling some analysis to the parser (which existed in parser 2) but beyond that we never touched it.

I continued to build with it but had not been actively testing the code. I am surprised at how well it run without any changes.

best
Prof. Victor Lazzarini
Maynooth University
Ireland

> On 29 Oct 2025, at 22:14, Steven Yi <[email protected]> wrote:
> 
> *Warning*
> 
> This email originated from outside of Maynooth University's Mail System. Do not reply, click links or open attachments unless you recognise the sender and know the content is safe.
> 
> 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
>> 
>> 
>> 
>> 
>> 
>>