From owner-cvs-all  Wed Aug 25 23:50:12 1999
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Message-Id: <199908260647.QAA21406@nymph.detir.qld.gov.au>
To: Alan Cox <alc@cs.rice.edu>
Cc: cvs-committers@freebsd.org, cvs-all@freebsd.org,
	syssgm@detir.qld.gov.au
Subject: Re: cvs commit: src/sys/vm vm_map.h 
References: <199908231808.LAA86314@freefall.freebsd.org> <199908250703.RAA14106@nymph.detir.qld.gov.au> <19990826013921.D27804@cs.rice.edu>
In-Reply-To: <19990826013921.D27804@cs.rice.edu>
    from Alan Cox at "Thu, 26 Aug 1999 01:39:21 -0500"
Date: Thu, 26 Aug 1999 16:47:07 +1000
From: Stephen McKay <syssgm@detir.qld.gov.au>
Sender: owner-cvs-all@FreeBSD.ORG
Precedence: bulk

On Thursday, 26th August 1999, Alan Cox wrote:

>On Wed, Aug 25, 1999 at 05:03:24PM +1000, Stephen McKay wrote:
>> Wouldn't it have been better to change the lock code to sleep on a field
>> within the lock structure, rather than the first byte?
>
>Yes and no.  :-)  Doing as you suggest is a great idea because it could
>reduce the chance of this same problem happening elsewhere in the kernel.
>(So, I would welcome a patch that implements it.)
>
>On the other hand, this patch fixes the problem at hand and has a near-zero 
>chance of causing any new problems.  I don't feel the same way about any
>changes to lockmgr, and since 3.x-STABLE is subject to the same problem,
>I wanted to try the simplest patch, that I wouldn't worry about MFC'ing,
>first.

Cogently argued.  I agree.

The change I suggest involves changing 1 tsleep and 4 wakeup calls in
kern_lock.c.  I'll try it out this weekend.  But anyone else with the
time right now can beat me to it, if they like.

Stephen.


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