Thoughts on software-defined silicon [LWN.net]

Thoughts on software-defined silicon

Posted Feb 22, 2022 1:28 UTC (Tue) by klossner (subscriber, #30046)
In reply to: Thoughts on software-defined silicon by tshow
Parent article: Thoughts on software-defined silicon

Many decades ago, my employer leased IBM 370/148 serial number 1. It was a lease not a purchase so we paid a monthly fee for the computing resource, and the fact that increasing RAM could be done by paying more each month to have a jumper moved was not philosophically troubling. It was analogous to renting a cloud server today.

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Thoughts on software-defined silicon

Posted Feb 22, 2022 9:46 UTC (Tue) by geert (subscriber, #98403) [Link] (3 responses)

Except that the unused cloud server capacity would be rented to someone else.

Software-defined silicon is like renting the first two floors in a 10-story office building which is otherwise vacant: if you pay more, you get access to more floors; if you don't, the other floors stay unused. But the other floors have been constructed anyway, and thus have already consumed (scarce) resources.

Thoughts on software-defined silicon

Posted Feb 25, 2022 17:02 UTC (Fri) by giraffedata (guest, #1954) [Link] (2 responses)

If this building is analogous to a processor, how has constructing the other 8 floors consumed scarce resources? It costs about the same to build a 10 story building as a a 2 story one if they're like processors.

And that's why the the owner doesn't make you pay for all 10 stories if you don't need them.

And the only reason he doesn't go ahead and let you use the other 8 anyway is that locking you out of them is the only way he can know you're telling the truth when you say you're willing to pay for only 2 stories. Charging people for all the stories they're willing to pay for minimizes the price per story for everyone.

Thoughts on software-defined silicon

Posted Feb 25, 2022 18:58 UTC (Fri) by geert (subscriber, #98403) [Link]

> If this building is analogous to a processor, how has constructing the other 8 floors consumed scarce resources? It costs about the same to build a 10 story building as a a 2 > story one if they're like processors.

The "10-story" processor still requires more raw material (silicon + whatever else for doping, etching, interconnects, ...). Plus, you can fit more "2 story" processors on the same wafer, so there's a processing cost, too.

Thoughts on software-defined silicon

Posted Feb 25, 2022 19:06 UTC (Fri) by nybble41 (subscriber, #55106) [Link]

As long as we're speaking in analogies, it's more like *buying* (not renting) the building but the seller only gives you the key to the first two stories. You are, after all, *buying* the entire CPU, even if parts of it are disabled by software keys.

The difference being that it's not a crime to pick or drill out some locks in your own building to access the upper floors. If you were actually renting the building (CPU) that would be a different matter. (And, of course, that the software locks in question are considerably more difficult to either pick or disable than, say, the lock on your average bank vault, much less a normal high-rise.)