[TUHS] non-blocking IO

[Peter Jeremy]

On 2020-Jun-01 07:58:02 -0700, Larry McVoy <lm at mcvoy.com> wrote:
>On Mon, Jun 01, 2020 at 01:32:56PM +1000, Dave Horsfall wrote:
>> On Mon, 1 Jun 2020, Rob Pike wrote:
>> 
>> > I???m not quite sure why the Research lineage did not include
>> > non-blocking behaviour, especially in view of the man page comments.
>> > Maybe it was seen as against the Unix philosophy, with select()
>> > offering sufficient mechanism to avoid blocking (with open() the hard
>> > corner case)?
>> >
>> >That's it. Select was good enough for our purposes.
>> 
>> After being dragged through both Berserkley and SysVile, I never did get the
>> hang of poll()/select() etc,,,
>
>I'm sure you could, select is super handy, think a network server like
>apache.

My view may be unpopular but I've always been disappointed that Unix
implemented blocking I/O only and then had to add various hacks to cover
up for the lack of asynchonous I/O.  It's trivial to build blocking I/O
operations on top of asynchonous I/O operations.  It's impossible to do
the opposite without additional functionality.

I also found it disappointing that poll()/select() only worked on TTY and
network operations.  HDDs are really slow compared to CPUs and it would be
really nice if a process could go and do something else whilst waiting for
a file to open.

-- 
Peter Jeremy
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