Date: Wed, 31 Jan 2001 23:47:31 -0800 From: Julian Elischer <julian@elischer.org> To: John Baldwin <jhb@FreeBSD.org> Cc: Matthew Emmerton <matt@gsicomp.on.ca>, freebsd-hackers@FreeBSD.org Subject: Re: Atomic bit operations Message-ID: <3A791493.FC414DEB@elischer.org> References: <XFMail.010131151628.jhb@FreeBSD.org>
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John Baldwin wrote: > > On 31-Jan-01 Matthew Emmerton wrote: > > Hi all, > > > > I've taken a look around for an implementation of atomic bit operations in > > FreeBSD (similar to Linux' asm/bitopt.h, which include clear_bit() and > > test_and_set_bit()) but haven't found any. The only thing I've found are > > the atomic clear/set/add/sub routines in machine/atomic.h. > > > > Do we have an implementation of atomic bit operations, and if we don't, > > would we like some? > > Erm, atomic_set() sets's bits, and atomic_clear() clear's bits. Anything else > you might need can be done with atomic_cmpset() anyways. Also, atomic > operations are very hard to debug, esp. to check for race conditions, so there > direct use is discouraged. Instead, use a higher level primitive such as a > mutex or other appropriate lock. There is also talk of a potential abstract > refcount type so that simple reference counts can be optimized, though that has > been shot down thus far. by who?? I really want this.... > > > -- > > Matt Emmerton > > -- > > John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ > PGP Key: http://www.baldwin.cx/~john/pgpkey.asc > "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message -- __--_|\ Julian Elischer / \ julian@elischer.org ( OZ ) World tour 2000-2001 ---> X_.---._/ v To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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