Re: [GD-General] cross platform 64bit lock free FIFO?

[Daniel V. <Dan...@ep...>]

> see (or vice versa), but on Intel, that can never happen.

FWIW, it can on next gen consoles though at least there are intrinsics
for inserting light weight memory barriers.

-- Daniel, Epic Games Inc. =20

> -----Original Message-----
> From: gam...@li...=20
> [mailto:gam...@li...]=20
> On Behalf Of Jon Watte
> Sent: Monday, August 07, 2006 2:29 PM
> To: gam...@li...
> Subject: Re: [GD-General] cross platform 64bit lock free FIFO?
>=20
> More than one question in the same message.
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> Typically, a lock-free FIFO supports only a single writer and=20
> a single=20
> reader. If that's all you need, then you don't even need the special=20
> instructions, because the writer will always write the same variable,=20
> and the reader will always read the other same variable. If=20
> your cache=20
> is not 100% read-after-write coherent, then you may have a temporary=20
> situation where there's something written that the reader doesn't yet=20
> see (or vice versa), but on Intel, that can never happen.
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> If you need multiple readers, or multiple writers, then correct=20
> lock-free implementation suddenly becomes a *lot* harder.
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> Cheers,
>=20
>                 / h+
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>=20
> Andras Balogh wrote:
> > I've found info on know how to implement a lock free FIFO on 32bit =20
> > systems, but I've also read that making it work for 64bit=20
> systems with the =20
> > current instruction sets is very difficult and extremely=20
> error prone. So I =20
> > would prefer to use a proven solution, instead of trying to=20
> roll my own. =20
> > On Windows, it's easy, because the Win32 API provides an=20
> interlocked =20
> > SList, that is supposed to work on 64 bit platforms too.=20
> But what about =20
> > other operating systems? Also, AFAIK these new 64bit=20
> systems don't really =20
> > have a 64bit address space, but 40-44? Does this mean, that=20
> all these =20
> > 64bit implementations are doing is only using the top 20=20
> bits for ABA =20
> > resolution?? I'm confused :)
> >  =20
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