3 ms·
Power consumption of DRAM is high, what are you talking about? DRAM requires constant refresh -- the whole reason DRAM can be high-density if because it is a 1-
by zxcv123 11y ago
Power consumption of DRAM is high, what are you talking about? DRAM requires constant refresh -- the whole reason DRAM can be high-density if because it is a 1-T cell with a trench capacitor -- but the capacitor needs to be refreshed on a synchronized basis (hence SDRAM) -- that was the big innovation.
And yes, array size affects latency but so does the underlying process technology (much more so across technologies).
- mmf 11y agoAs I did not have the numbers fresh in memory (apparently I needed a refresh ;) ) I googled for dram data sheet and got the first ddr3 PDF (Hynix). Quick, and very dirty math suggests that -refresh power is on the order of milliwats per Gigabyte -memory access is on the order of 0.1W per GB per second For refresh power, let's face it: it's puny. Regarding the active power, I have yet to see anything (off chip and this size) that is better than that. P.S. I did say active in my original post :)
- codebook 11y agoyou overlooked refresh time, which is around 7~8 ms. So, in order to keep the DRAM data alive, DRAM should consume a few tenths of Watt per Gigabyte per second, it is considerable amount of power.
- witty_username 11y agowatt per second makes little sense in this context watt != energy
- dooptroop 11y agoBut Watt * second IS energy.
- mmf 11y agoIt's W/GBps, or if you prefer simplifying J/GB. I like the former better, power and bandwidth are handier in real life computer science.
- witty_username 11y agoAh, it made sense now.
- mmf 11y agoA few corrections: -refresh period is more like 32-64ms -refreshing is way (way) cheaper than streaming data out since you refresh an entire word line, and you do not pay io cost, which is a significant fraction of the cost of accessing dram.