Date: Wed, 17 Jan 2001 11:14:49 -0500 (EST) From: Garrett Wollman <wollman@khavrinen.lcs.mit.edu> To: Alfred Perlstein <bright@wintelcom.net> Cc: current@FreeBSD.ORG Subject: Re: Atomic breakage? Message-ID: <200101171614.LAA18224@khavrinen.lcs.mit.edu> In-Reply-To: <20010116191009.E7240@fw.wintelcom.net> References: <3A64AA23.30035A1C@elischer.org> <Pine.BSF.4.21.0101171400210.3074-100000@besplex.bde.org> <20010116191009.E7240@fw.wintelcom.net>
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<<On Tue, 16 Jan 2001 19:10:10 -0800, Alfred Perlstein <bright@wintelcom.net> said: > Just wondering, can't you use 'LOCK addl' and then use 'LOCK addc'? > add longword, add longword with carry? I know it would be pretty > ugly, but it should work, no? The two bus cycles are independent, so there is a race condition. OTOH, it's a fairly *unlikely* race condition, and the worst thing that can happen is statistics that are obviously off by four billion. (The race only occurs when there is a carry out of the low-order longword, which is to say, once in every 2**32 operations.) -GAWollman To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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