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Re: question about UARTs support code in the kernel

This is a discussion on Re: question about UARTs support code in the kernel within the mailing.openbsd.tech forums, part of the OpenBSD category; --> Making, drinking tea and reading an opus magnum from Alexei G. Malinin: > Hello. > > Can anybody tell ...


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Old 02-18-2008, 08:12 AM
Michael Shalayeff
 
Posts: n/a
Default Re: question about UARTs support code in the kernel

Making, drinking tea and reading an opus magnum from Alexei G. Malinin:
> Hello.
>
> Can anybody tell me what is the idea of setting
> TX trigger to maximum? In this case we have
> no performance gain during servicing TX
> interrupts because, for example, when TX fifo
> is 64 bytes and TX trigger is 56 bytes and TX fifo
> is full - TX interrupt is activated after TX fifo
> transmits every 8 bytes if traffic is high.
> I think that setting TX trigger to minimum can
> give us performance gain because TX interrupt
> will be activated less frequently then in the
> above example and the kernel will have more time
> to service other tasks.


8 chars at 115200 be about 1000 ints/sec -- not a problem.
the problem at hands is to make sure there is always smth
in the tx buffer while interrupt is being serviced thus
avoiding stalls due to delys for the intr handler to
push new data into the tx buffer.

cu

--
paranoic mickey (my employers have changed but, the name has remained)

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