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Date: Tue, 16 Oct 2007 10:39:28 -0700
From: Jason Evans <jasone@freebsd.org>
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Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org,
	David Xu <davidxu@FreeBSD.org>, cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/lib/libthr/thread thr_pspinlock.c
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Kris Kennaway wrote:
> David Xu wrote:
>>   FreeBSD src repository
>>
>>   Modified files:
>>     lib/libthr/thread    thr_pspinlock.c   Log:
>>   Reverse the logic of UP and SMP.
>>     Submitted by: jasone
>>     Revision  Changes    Path
>>   1.6       +1 -1      src/lib/libthr/thread/thr_pspinlock.c
> 
> Are there any common applications that use this?

It's worth mentioning that this change, although correct, does not make 
a measurable performance difference for the tests I was running when I 
found the bug.  It is possible that making the spinlocks adaptive would 
help, but I didn't look into this.

(I was working on malloc performance enhancements that have turned out 
very nicely, but in the end I had to switch to hand-rolled "spin" 
mutexes that eventually convert to blocking, in order to avoid the 
possibility of unrecoverable priority inversion.)

Jason