4 ms·
As 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 v
by mmf 11y ago
As 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.