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Re: scheduling question

i have written a low latency coreaudio driver which
sends and receives UDP packets containing audio out
over the network interface to a special purpose piece
of hardware i've built. In order to get the
performance/latency/etc i needed when the machine was
running under a heavy load (doing real time processing
of live audio, etc) I had to modify the
AppleGMACEthernet.kext driver so that the main loop
in my coreaudio driver (get packet, copy buffers, call
taketimestamp, send a packet out) gets called at
primary interrupt time (highest priority in the
system) by using checkForInterrupt instead of just
interruptOccurred and having it call my coreaudio
driver. I basically bypassed the whole networking
stack.

You might need to do something of that sort...

-rimas

--- Mike Smith <email@hidden> wrote:
> On Jan 15, 2004, at 1:31 AM, Stefan Werner wrote:
>
> > Are there other tweaks to enhance the latency of
> networking? I don't
> > mind a decrease in throughput, I'm in one of the
> rare cases where
> > bandwidth is not the limit. There are these
> popular "bandwidth tuner"
> > tweaks where people change the system's TCP buffer
> size with sysctls,
> > would shrinking the buffers give me any latency
> improvements or will
> > that result in dropped packets?
>
> It won't help; the system already tries to give you
> the lowest possible
> latency. There's not really any more blood to
> squeeze from the stone.
>
> It's important, back in the design stage, to take
> into consideration
> that you're going to be running in a multiprogrammed
> environment and
> try to take this into account there, rather than
> trying to tweak a
> system that can't give you guarantees to fit a
> design that assumes a
> particular value of "reasonable".
>
> Obviously this isn't always possible.
>
> = Mike
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References: 
 >Re: scheduling question (From: Mike Smith <email@hidden>)



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