----- Original Message -----
From: Iwo Mergler <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, October 01, 2001 4:09 AM
Subject: Re: [rtl] RT-Linux patch proposal for RTF size
queryage
>
> Sorry for intruding in this discussion, but I would like
> to lobby in favour of the fifo_size function. :^)
>
> I have a real-world example here which requires a way to
> read the fill level of a fifo. I solved it by adding the
> function (macro) myself, but I would feel more
comfortable
> to use the official release.
>
> My hardware is capable of changing the data transfer rate
on
> request, but there is a long latency involved in this. At
> the time the fifo write fails, it is too late. In my
case,
> I use the fifo fill level to smoothly change the rate of
> the data transfer, allowing enough time for the hardware
> to adjust.
>
> Another, less serious benefit of fifo_size is the
coolness
> factor of having /proc/mydriver return "FIFO 34% full".
:^)
>
> Thanks,
>
> Iwo
> -- [rtl] ---
First, there's no need to apologize for adding another
voice to an intellectual discussion -- the more points of
view that are represented the more likely it is that all
concerned will make the best decisions.
Second, please don't interpret what I said as meaning
that a FIFO-fullness function is worthless. I have myself
hacked up an older version of RTLinux to make certain
normally internal FIFO routine variables public so I could
in fact do just that. What I was saying was that in the
most general setting it's worthless because of the
multi-tasking (or SMP) nature of the processing. I tried
to indicate that in certain controlled conditions like my
particular system I could guarantee that only two tasks
would ever use any one FIFO. The problem I see for that is
if someone else comes along to take up maintenance on my
system and doesn't fully appreciate the dangers then that
person could use the added features in an unsafe manner.
For particular systems it is a very worthwhile feature
which is IMO worthless in general. But unlike Victor and
company most of us are not in the business of writing
completely general software, we're only using RTLinux to
solve particular problems, each with its own unique
architectural features.
CAVEAT EMPTOR.
Norm
-- [rtl] ---
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