[linux-audio-dev] Re: [announce] [patch] Voluntary Kernel Preemption Patch

Ralf Beck musical_snake at gmx.de
Tue Jul 20 18:11:20 UTC 2004


> it's an issue for all block IO drivers that do IO completions from IRQ
> context and that can do DMA - i.e. every block IO hardware that uses
> interrupts. This includes SCSI too. In fact for SCSI it's a norm to have

I renew a question i asked earlier.

To my understanding, on a SMP or hyperthreading system, disabling of
IRQs is always local to one (virtual on HT) cpu.

So would it be possible to get ultralow latency by simply hardlock all irqs 
and processes to cpu1 and the irq triggering the audiothread (together with 
the audiothread) to cpu 2 using the sched_affinity and irq-affinity 
capabilites of the kernel?

This would be an easy to use lowlatency hardware patch for  linux audio users
with SMP/HT systems. Anybody knows?

I'm currently thinking about getting a new system and consider a dualsystem if 
this worked.

Ralf



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