[LAD] Faster context switch

Michael Ost most at museresearch.com
Tue Nov 2 17:17:30 UTC 2010


Paul Davis wrote:
> On Tue, Nov 2, 2010 at 12:53 PM, Michael Ost <most at museresearch.com> wrote:
>> Hi list,
>>
>> I am seeing what appears to be a 4 - 7 usec context switch time on a 3 GHz
>> Core 2 Duo machine with the 2.6 kernel, and 10 - 15 usecs on a 1.66 GHz
>> Atom. Is that reasonable? Does anyone have any tips on how to speed that up,
>> if possible?
<snip>
>> Since this has to happen twice per buffer, at a 32 sample buffer size and
>> with 10 VSTs, overhead accounts for about 14% of the CPU. On the slower Atom
>> machine, it would account for 33% of the CPU.
> 
> you can't reduce context switch times. the code involved is in the kernel.
> 
> it is precisely this problem that led to FST, and the more general use
> of FST by ardour (for example) where rather than going back and forth
> between wine and the linux app, the linux app becomes a wine process
> itself, and everything is in-process.

Ah, so no magic bullet then! %) This makes sense. Thanks for your response.

- Michael Ost



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