Date: Sun, 17 Dec 2000 21:13:09 -0700 From: Chuck Paterson <cp@bsdi.com> To: John Polstra <TrimYourCc@polstra.com> Cc: smp@FreeBSD.ORG Subject: Re: atomic increment? Message-ID: <200012180413.eBI4D9P17266@berserker.bsdi.com> In-Reply-To: Your message of "Sun, 17 Dec 2000 15:47:35 PST." <200012172347.eBHNlZ764346@vashon.polstra.com>
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John, I am pretty sure that what you said about the effects of volatile matches my understanding of what they do. I am less sure if we are saying the same thing about where they are needed. While the volatile can be left off of lots of operations, it still must be left on operations which are used for locking because there is no way the compile can no what the lock being acquired is protecting and therefore all computations following the operation must be done after the asm statement, discarding is partial results that may be laying around in a register. Which is what lead to my statement about the locked operation reducing register pressure in the first place :) Chuck To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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