Date: Mon, 03 Sep 2001 20:45:00 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: Alfred Perlstein <bright@mu.org> Cc: cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org, Jake Burkholder <jake@FreeBSD.org> Subject: Re: cvs commit: src/sys/sparc64/include atomic.h Message-ID: <XFMail.010903204500.jhb@FreeBSD.org> In-Reply-To: <20010903195424.T81307@elvis.mu.org>
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On 04-Sep-01 Alfred Perlstein wrote: > * Jake Burkholder <jake@FreeBSD.org> [010903 17:03] wrote: >> jake 2001/09/03 15:03:25 PDT >> >> Modified files: >> sys/sparc64/include atomic.h >> Log: >> Add atomic_load and store functions without membars, fwiw. >> >> Revision Changes Path >> 1.4 +25 -6 src/sys/sparc64/include/atomic.h > > My apologies, but these look wrong, my sparc v9 manual says > that although the atomic ops will work atomically without > membar... that if you don't use membar you don't know the > sequencing of the stores and loads surrounding the atomic > op, so if it is an atomic op to perform a lock, your memory > sequencing may cause accesses to a locked object before > the lock is aquired or at least allow memory accesses to > bleed through after the lock is released. > > Of course I could be smoking the good crack today, so take > this with a grain of salt. :-) They are still atomic, they just aren't very useful. :) -- 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 cvs-all" in the body of the message
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