Re: CVS commit: src/sys

[Tetsuya Isaki <isaki%pastel-flower.jp@localhost>]

At Sun, 29 Mar 2020 15:11:39 +0200,
Joerg Sonnenberger wrote:
> > CPU load or performance is not subject.  I know that my
> > implementation will work on the most modern real hardware.
> > But I feel that at least 4msec is too rush to be default.
> > A default should not be for one game application.
> 
> I would allow at least 1/HZ as baseline.

Thank you for comment.
Using HZ sounds interesting idea, but unfortunately this will not
make desired results (if what you are talking about can be written
like following).

----
#if !defined(AUDIO_BLK_MS)
# define AUDIO_BLK_MS (1000 / ((HZ > 1000) ? 1000 : HZ))
#endif
----

amd64 uses HZ=100 so that blk_ms=10.  It looks good.
alpha uses HZ=1024 (thanks thorpej@).  If we assume upper limit
HZ=1000, then blk_ms=1.  It works [*] but I think that it's a bit
small for default.
m68k often uses HZ=60~100 so that blk_ms=10~16.  This is obviously
too small for m68k default.

 [*] On my alpha (500MHz), wss(4)/ISA works even on blk_ms=1.
 But I was not able to set 1msec on yds(4) PCI sound card on
 the same machine.  Its lower limit was 5msec (due to driver's
 or hardware's restriction, I don't know details though).


By the way, I am planning the following.  How about this?

---- dev/audio/audiodef.h ----
#include <machine/audio_machdep.h>

#if !defined(AUDIO_BLK_MS)
# if defined(AUDIO_BLK_MS_MACHDEP) // or better name?
   /* Use machine dependent default if specified */
#  define AUDIO_BLK_MS AUDIO_BLK_MS_MACHDEP
# else
   /* Otherwise use MI default */
#  define AUDIO_BLK_MS (10)
# endif
#endif

---- arch/<modern_ports>/include/audio_machdep.h ----
/* Use MI default, see dev/audio/audiodef.h */
#undef AUDIO_BLK_MS_MACHDEP

---- arch/<antique_ports>/include/audio_machdep.h ----
#define AUDIO_BLK_MS_MACHDEP (100) // for example

----

Thanks,
---
Tetsuya Isaki <isaki%pastel-flower.jp@localhost / isaki%NetBSD.org@localhost>