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From: Terje Mathisen "terje.mathisen at on 25 Jul 2010 04:42 Robert Myers wrote: > Maybe you want more programmable control over coherence domains. If > you're not going to scrap cache and cache snooping, maybe you can > wrestle some control away from the hardware and give it to the > software. That sounds like software-controlled distributed shared memory, a concept that generates a lot more research papers and PhDs than actual useful products, at least so far. :-( Terje -- - <Terje.Mathisen at tmsw.no> "almost all programming can be viewed as an exercise in caching"
From: Robert Myers on 25 Jul 2010 14:05 On Jul 25, 4:42 am, Terje Mathisen <"terje.mathisen at tmsw.no"> wrote: > Robert Myers wrote: > > Maybe you want more programmable control over coherence domains. If > > you're not going to scrap cache and cache snooping, maybe you can > > wrestle some control away from the hardware and give it to the > > software. > > That sounds like software-controlled distributed shared memory, a > concept that generates a lot more research papers and PhDs than actual > useful products, at least so far. :-( > A PhD thesis that we both saw presented www.bunniestudios.com/bunnie/phdthesis.pdf dealt with a similar train of thought, except taking the exact opposite turn: doing even more to hide the hardware from the user of distributed memory. I understand much better now what he was trying to do. ;-) Robert.
From: Terje Mathisen "terje.mathisen at on 25 Jul 2010 14:23 Robert Myers wrote: > On Jul 25, 4:42 am, Terje Mathisen<"terje.mathisen at tmsw.no"> > wrote: >> Robert Myers wrote: >>> Maybe you want more programmable control over coherence domains. If >>> you're not going to scrap cache and cache snooping, maybe you can >>> wrestle some control away from the hardware and give it to the >>> software. >> >> That sounds like software-controlled distributed shared memory, a >> concept that generates a lot more research papers and PhDs than actual >> useful products, at least so far. :-( >> > > A PhD thesis that we both saw presented > > www.bunniestudios.com/bunnie/phdthesis.pdf Hmmm... Andrew "Bunnie" Huang I presume? Yes! I remember seeing that thesis, but I was chocked just now when I realized that it was from way back in 2002! > > dealt with a similar train of thought, except taking the exact > opposite turn: doing even more to hide the hardware from the user of > distributed memory. I understand much better now what he was trying > to do. ;-) Trying to define an architecture which could bypass as many of the (data) transport-related problems as possible, by making it extremely cheap to migrate sw threads instead? Terje > > Robert. > -- - <Terje.Mathisen at tmsw.no> "almost all programming can be viewed as an exercise in caching"
From: Robert Myers on 25 Jul 2010 15:06 On Jul 25, 2:23 pm, Terje Mathisen <"terje.mathisen at tmsw.no"> wrote: > Robert Myers wrote: > > On Jul 25, 4:42 am, Terje Mathisen<"terje.mathisen at tmsw.no"> > > wrote: > >> Robert Myers wrote: > >>> Maybe you want more programmable control over coherence domains. If > >>> you're not going to scrap cache and cache snooping, maybe you can > >>> wrestle some control away from the hardware and give it to the > >>> software. > > >> That sounds like software-controlled distributed shared memory, a > >> concept that generates a lot more research papers and PhDs than actual > >> useful products, at least so far. :-( > > > A PhD thesis that we both saw presented > > >www.bunniestudios.com/bunnie/phdthesis.pdf > > Hmmm... Andrew "Bunnie" Huang I presume? > > Yes! > > I remember seeing that thesis, but I was chocked just now when I > realized that it was from way back in 2002! > > > > > dealt with a similar train of thought, except taking the exact > > opposite turn: doing even more to hide the hardware from the user of > > distributed memory. I understand much better now what he was trying > > to do. ;-) > > Trying to define an architecture which could bypass as many of the > (data) transport-related problems as possible, by making it extremely > cheap to migrate sw threads instead? > Move the instructions to the data, I gather, rather than the other way around. That wouldn't help my problems. Robert.
From: Andrew Reilly on 25 Jul 2010 23:43
On Sat, 24 Jul 2010 16:52:22 -0700, MitchAlsup wrote: > I think what Robert is getting at is that lumping everything under a > coherent cache is running into a vonNeumann wall. Coherence is clearly complicated, but it doesn't seem necessarily to be sequential. Are there theoretical limits to how parallelisable coherence can be? Is the main issue speed-of-light limits to round-trip communication between distributed cache controllers? Cheers, -- Andrew |