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Date:      Tue, 04 Jun 2002 18:09:20 -0400 (EDT)
From:      John Baldwin <jhb@FreeBSD.org>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org
Subject:   RE: cvs commit: src/sys/kern kern_mutex.c
Message-ID:  <XFMail.20020604180920.jhb@FreeBSD.org>
In-Reply-To: <200206042153.g54LrmT07436@freefall.freebsd.org>

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On 04-Jun-2002 John Baldwin wrote:
> jhb         2002/06/04 14:53:48 PDT
> 
>   Modified files:
>     sys/kern             kern_mutex.c 
>   Log:
>   Optimize the adaptive mutex spin a bit.  Use a simple while loop with
>   simple reads (and on IA32, a "pause" instruction for each interation of the
>   loop) to spin until either the mutex owner field changes, or the lock owner
>   stops executing.
>   
>   Suggested by:   tanimura
>   Tested on:      i386

Not tested on Alpha SMP because SMP Alpha kernels aren't stable under load now.
I've had various lockups or weird NULL pointer bugs (as if a thread variable
passed down the stack suddenly became NULL) for a month or two now.  SMP sparc64
doesn't boot atm, hence no testing on it.

-- 

John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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