lkml.org 
[lkml]   [2004]   [Dec]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch] Real-Time Preemption, -RT-2.6.10-rc3-mm1-V0.7.33-0
Gene Heskett wrote:
> On Tuesday 14 December 2004 17:31, Ingo Molnar wrote:
>
>>* Lee Revell <rlrevell@joe-job.com> wrote:
>>
>>>On Tue, 2004-12-14 at 22:18 +0100, Ingo Molnar wrote:
>>>
>>>>the two projects are obviously complementary and i have no
>>>>intention to reinvent the wheel in any way. Best would be to
>>>>bring hires timers up to upstream-mergable state (independently
>>>>of the -RT patch) and ask Andrew to include it in -mm, then i'd
>>>>port -RT to it automatically.
>>>
>>>Among other things I think Paul Davis mentioned that George's high
>>>res timer patch would make it possible for JACK to send MIDI
>>>clock. This would be a huge improvement.
>>
>><clueless question> roughly what latency/accuracy requirements does
>>the MIDI clock have, and why is it an advantage if Linux generates
>>it? What generates it otherwise - external MIDI hardware? Or was
>>the problem mainly not latency/accuracy but that Linux couldnt
>>generate a finegrained enough clock?
>>
>>Ingo
>
>
> I'm not sure of the exact reasons, Ingo. But the midi clock is a
> bit of an odd man out in the normal progression of baud rates,
> its 31,250 baud, in case you didn't already know that.
>
> A lot of systems resort to a hardware timer driving a seriel shift
> register as I doubt if one could guarantee writing to a single
> bit port with an interval error of much more than 5% bit to bit,
> and cumulatively less than that for the overall byte. It can be
> done though, we have a program for the coco's that run on a .89
> mhz clock that can actually drive the seriel port well enough to
> run a midi keyboard plugged into it. I've run it, and it has
> enough spare time that I can steer some instruments to a second
> homemade midi pack plugged into its expansion interface at the
> same time & no descernable squiggles in the beat of the music.
>
> Did you see my comment about the later versions seeming to slow
> seti a wee bit? Other than that, I'm in love with this, the
> whole system just plain feels better. The only thing on my wish
> list right now is to be able to shut tvtime up, it grows the
> system log about a megabyte a minute with its missed read reports.
> Or is it tvtime that needs help?
>

Are you referring to the "Read missed before next interrupt" messages?
If so, you can disable this by disabling the rtc histogram under:
Device Drivers --> Character devices --> Real Time Clock Histogram Support.

kr
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:08    [W:0.902 / U:2.460 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site