Date: Wed, 31 Jan 2001 15:16:28 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: Matthew Emmerton <matt@gsicomp.on.ca> Cc: freebsd-hackers@FreeBSD.org Subject: RE: Atomic bit operations Message-ID: <XFMail.010131151628.jhb@FreeBSD.org> In-Reply-To: <016801c08bbb$d29a32c0$1200a8c0@gsicomp.on.ca>
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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. > -- > 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
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