Reiner Pope: preference

Transcript context

…Five minutes versus one hour. Exactly. I think this will probably end up being the drain time of the memory tier that you’re in. What that means is, given that I know I’m going to be holding something for five minutes, I would like to pick a memory that I can read every five minutes. I can read the whole memory once per five minutes, ballpark. That is the drain time of the memory. So if I take the storage capacity over storage bandwidth, I would like this to be equal to five minutes. We did this calculation for HBM. For HBM, we know that this number is 20 milliseconds. So HBM is much too small. DDR could be about an order of magnitude or two off from this, so this is probably on the order of seconds, like 1 to 10 seconds. I don’t have these numbers memorized, but generally, as you go to slower tiers, flash is plausibly on the order of one minute. And then spinning disk, which is massively different, is on the order of one hour. So this might actually identify the tiers of flash and spinning disk. Sorry, why is this the calculation? This is the storage capacity divided by the bandwidth?…

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