From owner-freebsd-arch  Tue Sep  3 23:35: 8 2002
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Date: Wed, 4 Sep 2002 16:42:19 +1000 (EST)
From: Bruce Evans <bde@zeta.org.au>
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To: Julian Elischer <julian@elischer.org>
Cc: John Baldwin <jhb@FreeBSD.ORG>, <arch@FreeBSD.ORG>,
	Alfred Perlstein <bright@mu.org>
Subject: Re: Process/thread states.
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On Tue, 3 Sep 2002, Julian Elischer wrote:

> On Tue, 3 Sep 2002, John Baldwin wrote:
>
> > ... (I don't
> > see why just using == to check a thread state is all that hard).
>
> because it in some cases actually becomes: (due to the fact thst you
> can be on the sleep queue AND teh run queue)
> #define TD_ON_RUNQ(td) (((td)->td_state & TD_BASE_MASK) == TD_ST_RUNQ)
> as you have to separate out the sleep queue bit.
> ...
> Do you really want to type that sort of test everywhere?
> By making it a macro we can keep the implementation of this state
> hidden. e.g if we move the RUNQ part of the state to td_flags
> to make it independently testable, the rest of the code doesn;t have to
> know how we optimised this. (we are discussing this exact change now).
> similarly for swapped.. or other states.

Just don't forget to change it back to a simple test once you have debugged
and optimized it :-).  One virtue of inline code is that it inhibits expansion
of huge macros to huger ones.

Bruce


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