Date: Wed, 26 Dec 2001 17:16:28 +0100 (CET) From: Michal Mertl <mime@traveller.cz> To: John Hanley <jh_@yahoo.com> Cc: arch@freebsd.org Subject: Re: 64 bit counters Message-ID: <Pine.BSF.4.41.0112261654060.20665-100000@prg.traveller.cz> In-Reply-To: <20011226005810.5475.qmail@web10102.mail.yahoo.com>
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On Tue, 25 Dec 2001, John Hanley wrote: > My only caution is this: > > On some platforms, 64 bit ints are not atomically written. > First 32 bits is written, then the remaining 32. If, say, > only the bottom half of the kernel accesses the counter, What do you mean by "the bottom half of the kernel"? > then likely all is well. If an interrupt routine can read > or write in the middle of a non-atomic operation, then all > hell can break loose, in ways that are extremely difficult > to track down because they only happen rarely. > Well I didn't think of that but I believe it shouldn't be that much a problem. At most the counter could become wrong :-). -- Michal Mertl mime@traveller.cz To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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