Date: Tue, 01 Jan 2002 14:01:49 -0800 From: Mike Smith <msmith@freebsd.org> To: Bernd Walter <ticso@cicely9.cicely.de> Cc: arch@FreeBSD.ORG Subject: Re: When to use atomic_ functions? (was: 64 bit counters) Message-ID: <200201012201.g01M1nr02027@mass.dis.org> In-Reply-To: Your message of "Tue, 01 Jan 2002 22:30:33 %2B0100." <20020101213033.GB9899@cicely9.cicely.de>
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> On Tue, Jan 01, 2002 at 12:48:34PM -0800, Mike Smith wrote:
> > > MBs are not needed for the variable itself, but they are making this
> > > family of functions very expensive.
> > > It's not very wise to handle counters with atomic_ functions unless
> > > the need to have MBs in them is not removed.
> >
> > It's imperative to use atomic operations for counters on SMP systems.
>
> But there is absolutely no need for MBs just to handle counters.
So fix the atomic functions on the Alpha so that the mb's are only
present when the cache-related semantics (acquire/release) are specified.
--
... every activity meets with opposition, everyone who acts has his
rivals and unfortunately opponents also. But not because people want
to be opponents, rather because the tasks and relationships force
people to take different points of view. [Dr. Fritz Todt]
V I C T O R Y N O T V E N G E A N C E
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