7 ms·
This article is specifically about another level of cache between L3 and main memory becoming standard in modern PC architectures. It has already happened in a
by BubRoss 7y ago
This article is specifically about another level of cache between L3 and main memory becoming standard in modern PC architectures.
It has already happened in a few places not mentioned in the article, Xeon Phi with high bandwidth memory and broadwell CPUs that could embedded ram as either video memory or a level 4 cache.
- ncmncm 7y agoThe point is that there is nothing at all special about cache vs any other kind of memory. There are purely practical distinctions made according to relative timing vs bus cycles and, at times, interrupt latency and head-arm settling time, that dictate the mechanism for faulting in misses. All these times have varied by many orders of magnitude over the years without producing any fundamental change in the principles involved. It's all just memory hierarchy, and has been for fully seven decades, since the very beginning. It takes a very small time window, and very limited historical awareness, to see Ln, for any n, as indicating anything special. In this case, it indicates what we have lately called "RAM" will now be called "L4" -- just as what was so recently RAM is now L3 -- as persistent phase-change memory moves into the place lately occupied by disks and, more recently, SSDs, and the distinction between "RAM" and "storage" gets fuzzy once again. Even persistence across power loss has phased in and out, over the decades. The slowest memory happens to now be both random-access and persistent, again, and pretty darn fast this time.
- BubRoss 7y agoNot only is that not true, that's not the point of this article at all. It is only talking about speculation for when a L4 cache will be added to modern architectures. > It takes a very small time window, and very limited historical awareness, to see Ln, for any n, as indicating anything special. This article actually goes through the history of cache additions and talks about how it isn't special and more a matter of evolution. You seem to be arguing against points no one is making. > it indicates what we have lately called "RAM" will now be called "L4" This is a bizarre semantic game to play, since cache is fundamentally about a heirarchy of locality and main memory is a way for the entire computer to communicate through storage that may or may not use the CPU.
- ncmncm 7y agoWhat is bizarre is pretending to understand what you read better than other people, while supporting your argument by directly contradicting what it actually says right there in black and white.
- BubRoss 7y agoYour replies had nothing to do with the article at all. Respond with actual information or not at all please.
- dang 7y agoWould you please stop posting in the flamewar style to HN? We've had to ask you this before. Continuing to do it eventually ends in your account getting banned. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html