From owner-freebsd-arch  Wed May 23  8:23:47 2001
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Date: Wed, 23 May 2001 11:23:32 -0400 (EDT)
From: Garrett Wollman <wollman@khavrinen.lcs.mit.edu>
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To: Brian Somers <brian@Awfulhak.org>
Cc: freebsd-arch@FreeBSD.ORG
Subject: Re: RFC: unit_list routines 
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<<On Wed, 23 May 2001 09:15:41 +0100, Brian Somers <brian@Awfulhak.org> said:

> The rman stuff seems to be overkill:

> o It uses a global mutex when allocating resources.

...which you can ignore...

> o It has a local mutex for waiting on resources (and an RF_ACTIVE flag).

...which you can also ignore...

> o It supports RF_SHARABLE/RF_TIMESHARE resources (I guess this isn't 
>   an overhead, just unnecessary).

...which you can also ignore...

> o It's implemented in terms of ``struct resource *''s, most of which 
>   inappropriate.

Inappropriate in what way?

> o It mucks about with device structs when reserving resources

...which you can just pass as a null pointer....

> Do you really think it's appropriate to try to re-use the rman stuff 
> for what I want to do ?

Given that the code is already there, and is already compiled into
every kernel, and (I hope) already has the bugs worked out, I would
suggest that it would not be a bad thing.

OTOH, if all you are doing is keeping an array of one-bit flags, and
having an arbitrarily-large upper limit on the number of devices is
acceptable, it's probably cheaper to just do it with a few macros.

-GAWollman


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