Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3

[Ingo Molnar]

* Michael K. Edwards <medwards.linux@xxxxxxxxx> wrote:

> 4) AIO vsyscalls whose semantics resemble those of IEEE 754 floating 
> point operations, with a clear distinction between a) pipeline state 
> vs. operands, b) results vs. side effects, and c) coding errors vs. 
> not-a-number results vs. exceptions that cost you a pipeline flush and 
> nonlocal branch.

threadlets (and syslets) are parallel contexts and they behave so - 
queuing and execution semantics are then ontop of that, implemented 
either by glibc, or implemented by the application. There is no 
'pipeline' of requests imposed - the structure of pending requests is 
totally free-form. For example in threadlet-test.c i've in essence 
implemented a 'set of requests' with the submission site only interested 
in whether all requests are done or not - but any stricter (or even 
looser) semantics and ordering can be used too.

in terms of AIO, the best queueing model is i think what the kernel uses 
internally: freely ordered, with barrier support. (That is equivalent to 
a "queue of sets", where the queue are the barriers, and the sets are 
the requests within barriers. If there is no barrier pending then 
there's just one large freely-ordered set of requests.)

	Ingo
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