From owner-freebsd-smp  Sun Nov 26 10:30:59 2000
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Date: Sun, 26 Nov 2000 10:30:57 -0800
From: Alfred Perlstein <bright@wintelcom.net>
To: smp@freebsd.org
Cc: jhb@freebsd.org
Subject: sysctl for DEBUG_MUTEX?
Message-ID: <20001126103056.T8051@fw.wintelcom.net>
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I was wondering if it was possible to change DEBUG_MUTEX such that
it sets up a sysctl that one could flip on and off so that those
of us using it only have to pay the penalty when we're interested
in the debugging.  Tor Egge explained that he doesn't have the
painfully slow disk access when he removes the DEBUG_MUTEX option.

I'm going to take a quick look at it, the idea would be to hook a
sysctl proc (sysctl handler) that would setup/teardown the DEBUG_MUTEX
state.

We'd still need a global lock for the linked list of mutexes,
however all the expensive validation stuff would be done only when
the sysctl was on, otherwise they'd just be linked together.

John has been working on the mutex stuff for quite a while and if
he wanted to do this it would probably go a lot smoother that if
I tried. *nudge* :)

-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."


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