sound driver for RTAI

[Paolo Mantegazza]

Jan Kiszka wrote:
> Paolo Mantegazza wrote:
> 
>> Thomas Witzel wrote:
>>
>>>
>>> I'm very interested in this topic and started working on an Audigy 
>>> driver derived from the ALSA code base. I didn't have too much time 
>>> for this yet.
>>> I was thinking of using fusion. Whats the reason to prefer magma ?
>>>
>>
>> Recall: we are talking of direct within the acustic band processing!!!
>>
>> - Machine: dual PIII, 1GHz, ADEOS r12 (as available within magma, not 
>> the official one) for Linux-2.6.12.
>>
> 
> Adeos for 2.6.12 seems to be broken (we are already getting lock-ups on 
> insmod rtai_hal). Did you also try on 2.6.11 or older kernels as well?
> 

In the acustic band it has always been so. Even if do not show up on 
this list I'm a hard fusion tester and always let Philippe know my findings.

>> - Load: X opened, "ping -f -s1500 somewhere", "dd if=/dev/hdb2 
>> of=/dev/null bs=1M count=1000".
>>
>> + Native fusion latency.c run at 50 Khz:
>>
>> == Sampling period: 20 us
>> RTT|  00:00:01
>> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat 
>> best|---lat worst
>> RTD|        4200|        5728|       24315|      20|        4200| 24315
>> RTD|        4340|        5830|       47553|      54|        4200| 47553
>> RTD|        4036|        5737|       43138|      81|        4036| 47553
>> RTD|        2130|        7257|       42522|     364|        2130| 47553
>> RTD|        2333|        5838|      236254|     410|        2130| 236254
>> RTD|        4402|        5778|       42390|     423|        2130| 236254
>> ---|------------|------------|------------|--------|------------------------- 
>>
>> RTS|        2130|        6028|      236254|     423| 00:00:07/00:00:07 
>> (i.e. a 7 second run)
> 
> 
> This is likely a bug, not a design problem. The latencies we measured 
> even on smaller systems (Pentium I 133 MHz) over longer periods are not 
> that extrem, a bit higher than classic (due to the strictly layered 
> design of fusion), but acceptable for common applications. The latency 
> numbers I recall for a Pentium M, 1,3 GHz: < 20 us. Not tested with 
> latest fusion and kernel release, but rather constant over the last 
> versions.

You are likely thinking UP, where even magma is far better. Moreover you 
forgot we are talking of "acustic band" real time, not the usual at most 
1 ms PID stuff.

Please notice that it is neither a matter of I like this or that nor 
this is better than that, even if anybody can have his/her own idea.

We are within the RTAI family and as such there are plenty of choices 
and backups.

Paolo.