Subject: Re: [linux-audio-dev] laaga implementation news bite
From: Paul Davis (pbd_AT_Op.Net)
Date: Mon Jun 11 2001 - 14:50:32 EEST
In message <3B2390AB.8035A84D_AT_alsa-project.org>you write:
>Paul Davis wrote:
>>
>> >I don't understand of what you're speaking: in my design for multi
>> >process model the switch back to the engine happens only once for each
>> >period (as it's needed).
>>
>> Yes, but thats because your example didn't solve a rather fundamental
>> problem of resorting the graph.
>
>It seems you're rather confused... nobody expected that that program
>solves that...
thats not what i meant. of course i didn't *expect* it to solve that
problem. the problem, however, is a significant one. once you have
dynamic numbers of clients and reconfigurations of the flow graph, its
a lot of work to reconnect them all to each other in a way that avoids
switching back to the engine. its not impossible, just a lot of work.
>This is what I'm referring and seen the presence of SCM_RIGHTS in
>http://www.opengroup.org/onlinepubs/7908799/xns/syssocket.h.html I
>suppose you don't remember correctly.
well, i guess i was remembering the early (1998) debates over whether
to use sysv-style or bsd-style fd-passing, and so i concluded that
this wasn't part of POSIX. OTOH, it would appear to me that it still
isn't part of POSIX. the single unix spec is very definitely not
POSIX. maybe i should be willing to just go with Linux, but POSIX
seems like a better platform standard to me.
>> >Note also that signals may have some non atomicity troubles.
>>
>> such as?
>
>Go to sleep *after* signal has been received (same problems that's faced
>with pthread_cond_wait semantic).
Nope. sigblock/sigsuspend/sigpending take care of that.
As I said to Richard, I don't really care about the internal
implementation that much as long as it works. kill(2) just seemed to
me much more amenable to the kind of system we need. i don't think
that it *can't* be done with writing to an fd, but i think its a lot
more work.
--p
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