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To: Marc Slemko <marcs@znep.com>
cc: Charles Mott <cmott@srv.net>, hackers@FreeBSD.ORG
Subject: Re: flock() question 
In-reply-to: Your message of "Thu, 27 Nov 1997 23:51:22 MST."
             <Pine.BSF.3.95.971127234335.27255C-100000@alive.znep.com> 
From: David Greenman <dg@root.com>
Reply-To: dg@root.com
Date: Fri, 28 Nov 1997 03:07:25 -0800
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>Hmm.  It looks like if you have multiple processes blocked on the
>same lock in FreeBSD (well, 2.2 anyway), they are all woken up when
>the lock is freed.  Yes, only one will get the lock but they will
>all be woken.  Unless I am reading the code wrong...  This is in
>contrast to multiple processes blocking in accept(), where only
>one will be woken up.

   The optimized wakeup case for accept() is that way because I optimized
it. :-) You're probably right about flock(), but I haven't gotten around to
looking at that and other potential wakeup optimizations. Changes like that
have to be made with great care...what seems obvious often doesn't turn out
that way. :-)

-DG

David Greenman
Core-team/Principal Architect, The FreeBSD Project