Re: Winmodem support, some performance tradeoff estimates

Alan Cox (alan@lxorguk.ukuu.org.uk)
Sun, 16 Aug 1998 21:50:14 +0100 (BST)


> specifications secret, please always identify the specific chips for
> which specifications are not available, and, ideally, who contacted
> these vendors and when. If you are going to make architectural

I poked around USR a bit when I worked for 3com (ie after the 'merger')
and got no progress.

> in the cost/performance tradeoffs. Otherwise, please just admit to
> the current shortcoming in the Linux kernel (nobody has yet written a
> free soft modem stack), so that people will continue to trust what you

Amusing side exercise. List the patent licenses required for a 33.6
modem remebering in the US the USPO has some odd ideas about patenting
pure maths.

> o It can be argued that Linux users will collectively
> waste $100+ million in the absense of winmodem
> Linux drivers.

You claim the CPU difference is $6. Ok where are the numbers from. Digitals
own figures for a 200Mhz strongarm SA110 and their commercial software
mode is 25% of the resources of the chip. The real issue though appears
to be entirely patents and chip documentation.

> means the performance of using a soft modem is about 8 Pentium MHz,
> on the grounds that 1 32-bit Pentium MHz =~ 1 64-bit R4000 MHz in the

Way off. Firstly Im dubious about the 8Mhz, secondly the R4K's tend to
have DSP instructions (ones that are useful). Pentiums dont have an
add/multiply with no stall instruction once per clock.

Alan

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