Re: (reiserfs) Re: More on 2.2.18pre2aa2

[Martin Dalecki]

Hans Reiser wrote:
> 
> I really think Rik has it right here.  In particular, an MP3 player needs to be able 
>to say, I have
> X milliseconds of buffer so make my worst case latency X milliseconds.  The number 
>of requests is
> the wrong metric, because the time required per request depends on disk geometry, 
>disk caching, etc.
> 

No the problem is that an application should either: 

1. Take full controll of the underlying system.
2. Don't care about selftuning the OS.

Becouse that's what operating systems are for in first place: Letting
the
applications run without care of the underlying hardware.

Linux is just mistaken by desing that there should be a generic elevator
for any block device sitting on a single queue for any kind of attached
device. Only device drivers know best how to handle queueing and stuff
like
this. The upper layers should only car about semanticall correctness of
the
request orders not about optimization of them.
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