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| Message-ID | <4DCF1B96.6090106@SPAM.comp-arch.net> (permalink) |
|---|---|
| Date | 2011-05-14 17:17 -0700 |
| From | "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> |
| Organization | comp-arch.net |
| Newsgroups | comp.arch |
| Subject | Re: What are the various alternate uses for the PC's LSB ? |
| References | (1 earlier) <iqhv4i$bg8$1@speranza.aioe.org> <4DCCA664.9070207@SPAM.comp-arch.net> <nqev98-qvt2.ln1@ntp6.tmsw.no> <iqjjk2$ldo$1@dont-email.me> <op70a8-sru2.ln1@ntp6.tmsw.no> |
On 5/13/2011 10:53 AM, Terje Mathisen wrote: > Stephen Fuld wrote: >> On 5/13/2011 3:47 AM, Terje Mathisen wrote: >> >> snip >> >>> Personally I prefer algorithms which can use XADD, i.e. atomic >>> fetch_and_add(), specifically because they can provide guaranteed >>> forward progress, with minimum bus uglyness. >> >> I agree with your preference and would add another reason. There are >> applications where a system wide unique, guaranteed increasing >> number is exactly what is needed. Think transaction numbers in some >> transaction systems. XADD provides this with minimal cost. > > I know that such numbers are very useful, but I would really prefer to > avoid the need for them, because they do end up as a global bottleneck. >> >> >>> It should also be relatively easy (for hw) to propagate an XADD >>> operation across a mesh and handle it at the location of the target >>> memory. >> >> Yes. Although test and set is perhaps easier to do this with. But see >> below > > Test&Set, in the form XCHG reg,[mem] is the original x86 sync primitive, > the main problem is that it only provides a boolean gate, not something > which can be used as-is. Nit-pocking: XCHG is atomic exchange, not test-and-set. test-and-set is something more primitive.
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Re: What are the various alternate uses for the PC's LSB ? "Paul A. Clayton" <paaronclayton@gmail.com> - 2011-05-12 08:49 -0700
Re: What are the various alternate uses for the PC's LSB ? whygee <yg@yg.yg> - 2011-05-13 02:01 +0200
Re: What are the various alternate uses for the PC's LSB ? "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-12 20:32 -0700
Re: What are the various alternate uses for the PC's LSB ? Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-13 12:47 +0200
Re: What are the various alternate uses for the PC's LSB ? Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-05-13 08:44 -0700
Re: What are the various alternate uses for the PC's LSB ? Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-13 19:53 +0200
Re: What are the various alternate uses for the PC's LSB ? Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-05-13 11:36 -0700
Re: What are the various alternate uses for the PC's LSB ? Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-13 22:26 +0200
Re: What are the various alternate uses for the PC's LSB ? "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-14 17:17 -0700
Re: What are the various alternate uses for the PC's LSB ? Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-05-16 14:22 +0200
Re: What are the various alternate uses for the PC's LSB ? "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-16 07:38 -0700
Re: What are the various alternate uses for the PC's LSB ? "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-05-14 17:14 -0700
Re: What are the various alternate uses for the PC's LSB ? rpw3@rpw3.org (Rob Warnock) - 2011-05-13 07:45 -0500
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