Did IBM Just Preview The Future of Caches?

By: vonk (nope.delete@this.sun.com), September 15, 2021 8:58 am
Room: Moderated Discussions
Kester L (nobody.delete@this.nothing.com) on September 2, 2021 8:45 am wrote:
> https://www.anandtech.com/show/16924/did-ibm-just-preview-the-future-of-caches
>
> > The concept is that the L2 cache isn’t just an L2 cache. On the face of it, each L2 cache is
> > indeed a private cache for each core, and 32 MB is stonkingly huge. But when it comes time for
> > a cache line to be evicted from L2, either purposefully by the processor or due to needing to make
> > room, rather than simply disappearing it tries to find space somewhere else on the chip. If it
> > finds a space in a different core’s L2, it sits there, and gets tagged as an L3 cache line.
>
> I'm just wondering, but is there any precedent for doing a shared virtual L3 cache across multiple
> physical L2 caches? And why would someone want to go for such a baroque cache design?

SPARC M7 did a similar thing but only between the 8 L3 caches on chip. Each L3 could act as a victim cache for any other L3, for example if all cores attached to that partition were parked. The advantage was that when most of the cores on the chip are idle, a single core can use more of all of the on-chip cache capacity. Or in other words, achieve a better SPECcpu speed score.
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TopicPosted ByDate
Did IBM Just Preview The Future of Caches?Kester L2021/09/02 08:45 AM
  Did IBM Just Preview The Future of Caches?sr2021/09/02 09:23 AM
  Did IBM Just Preview The Future of Caches?---2021/09/02 09:28 AM
  Did IBM Just Preview The Future of Caches?dmcq2021/09/02 09:30 AM
  Did IBM Just Preview The Future of Caches?Rayla2021/09/02 07:04 PM
  Did IBM Just Preview The Future of Caches?Gabriele Svelto2021/09/03 07:28 AM
    Did IBM Just Preview The Future of Caches?Gionatan Danti2021/09/04 01:31 PM
      Did IBM Just Preview The Future of Caches?Michael S2021/09/04 01:54 PM
        Did IBM Just Preview The Future of Caches?Gionatan Danti2021/09/05 05:22 AM
  Did IBM Just Preview The Future of Caches?vonk2021/09/15 08:58 AM
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