Re: 25 microseconds?

There is a "rule of thumb" I have used for decades, and I have heard touted
in every seminar I have sat in --- you take as much time in your ISR as you
need; no more and no less. Draining the serial FIFO in the ISR is by better
than sipping one character at a time since each character in the FIFO is
going to cause another interrupt to be thrown which will incur additional
overhead. Moving all of the data from the FIFO to a software ring buffer
takes much less time than incurring interrupt overhead for every character.

--
The personal opinion of
Gary G. Little

"Richard Lee" <richard.lee@xxxxxxxx> wrote in message
news:1112893167.700666.244360@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Just my opinion, the DPC is not a magic bullet.
> Both ISR and DPC execution can kill performance.
> I guess that's why Microsoft limits both.
>
> I'm the last person to defend LPC.
> OEM's like it because it's cheap. So I support it.
>
> Anyway, I better quit while I'm ahead. I saw an old
> posting from Eliyas Yakub where he said:
> ISR - 10 microseconds
> DPC - 25 microseconds
> Yikes!
>
>


.

Relevant Pages

  • Re: 25 microseconds?
    ... Draining the serial FIFO in the ISR is by better ... than sipping one character at a time since each character in the FIFO is ... ISR - 10 microseconds ...
    (microsoft.public.development.device.drivers)
  • Re: Linux serial port dropping bytes
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    (comp.arch.embedded)
  • Request for comments - kgets()
    ... macro and a function-like macro macros below) ... pointers, dereferencing pointers, pointer arithmetic, and how (at ... character by character I can discuss a conceptual model of the ... FIFO Model - A block of memory having two pointers. ...
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  • Re: reading on serial port slow...
    ... FIFO has some characters waiting but no new ones have arrived ... IIRC "a while" is a few character times. ... the port to signal an interrupt after each character. ...
    (comp.os.linux.development.system)
  • Re: mscomm in vc++ - parity error
    ... ClearCommError reports the possible error condition before ... family UARTs can be problematic if the Rx FIFO is enabled. ... are several unprocessed bytes in the FIFO when the parity error ... represent the status of the current received character. ...
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