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Source paper linked is https://aisystemcodesign.github.io/papers/isca26/vistara_camera_ready.pdf https://aisystemcodesign.github.io/papers/isca26/vistara_cam...
by pjc50 4mo ago
Source paper linked is https://aisystemcodesign.github.io/papers/isca26/vistara_camera_ready.pdf https://aisystemcodesign.github.io/papers/isca26/vistara_cam...
From a quick skim, you could think of this as roughly equivalent to shoving a large amount of DDR4 on a PCIe card and using it as a swap space. It's more sophisticated (see CXL protocol), but that gives you an idea of the tradeoffs. It seems there is some OS-level support for moving hot/cold pages between the main fast DRAM and the expansion higher latency DRAM.
It's a very valid point that DRAM has a fairly long lifetime and contains significant embedded carbon emissions, as well as the current availability crisis of new DRAM.
- herodoturtle 4mo ago> and contains significant embedded carbon emissions Hi - thanks for the insightful comment - could you please expand on the above? Genuinely curious :)
- lmz 4mo ago"a lot of carbon was emitted while making it"
- NDlurker 4mo agoReduce, reuse, recycle
- pjc50 4mo agoFrom the paper: "Second, memory dominates the carbon footprint of the fleet [8], accounting for 69% of CO2 emissions and posing a significant sustainability challenge [4]. DRAM dominates datacenter embodied CO2 largely because it is ubiquitous and deployed in large quantities across essentially all servers. Based on our internal fleet data, and aligned with studies from other hyperscalers such as Microsoft [33], memory is one of the largest single embodied-emissions contributors" [8] U. Gupta, M. Elgamal, G. Hills, G.-Y. Wei, H.-H. S. Lee, D. Brooks, and C.-J. Wu, “ACT: Designing Sustainable Computer Systems with an Architectural Carbon Modeling Tool,” in Proceedings of the 49th Annual International Symposium on Computer Architecture (ISCA’22), 2022. [4] D. Azevedo, M. Patterson, J. Pouchet, and R. Tipley, “Carbon usage effectiveness (cue): A green grid data center sustainability metric,” White paper, vol. 32, 2010. [33] J. Wang, D. S. Berger, F. Kazhamiaka, C. Irvene, C. Zhang, E. Choukse, K. Frost, R. Fonseca, B. Warrier, C. Bansal, J. Stern, R. Bianchini, and A. Sriraman, “Designing Cloud Servers for Lower Carbon,” in Proceedings of the 51st Annual International Symposium on Computer Architecture, ser. ISCA ’24, 2025, p. 452–470. Not a reference, but I found https://www.interface-eu.org/publications/semiconductor-emission-explorer https://www.interface-eu.org/publications/semiconductor-emis... which goes into great detail on the subject. I hadn't realized there were significant emissions of fluorinated gases directly from the fabs, which is mildly alarming. Although it looks like there has been a crackdown on this either politically or through ESG policies.
- yieldcrv 4mo ago> recycle pls > not like that this is insightful to me as well, I'm glad to know modern memory is less polluting in use but now I wonder about how it compares to the manufacturing process
- ryukoposting 4mo agoI see what you did there.
- Barbing 4mo agoSettle a debate? https://news.ycombinator.com/item?id=48888401 https://news.ycombinator.com/item?id=48888401 :)
- jonhohle 4mo agoI’ve wanted this for a long time and it seems to reemerge during RAM boom cycles and then disappear during busts. I have 32GB of DDR3 that would be great for scratch space or cache of i could throw it on a card.