Subject: Re: [alsa-devel] Re: [linux-audio-dev] laaga, round 2
From: Paul Davis (pbd_AT_Op.Net)
Date: Tue May 15 2001 - 18:01:33 EEST
I wrote:
>> context switch costs that we've been discussing, the cost of zeroing
>> memory goes down more or less linearly with processor speed (helped
>> along by RAM speed, which is increasing much more slowly). Because of
>> this, we should consider the cost to zero a buffer to be an
>> essentially vanishing item in the overall operation of an audio
>> system.
Abramo replied:
>I think you should have benchmarked this statement before to write it
>;-)
I have. Re-read what I wrote. I know that there are real costs of
zeroing the buffer and using "+=". But that cost is almost linear with
CPU speed. You speak often of planning for the future. The cost right
now is quite manageable, and will only get smaller. The benefit of
adopting this model is immense in terms of simplicitly. To design a
system in which we create complexity to solve a *vanishing* problem
seems foolhardy to me.
Contrast this to the costs of IPC, which do not scale linearly with
CPU speed, and will never really vanish until we are all using 64 bit
operating systems that use a single address space (i.e. the TLB is
never flushed). Such operating systems do exist, but only in CS and
R&D departments.
--p
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