Xbitlabs have seen a document which reveals the cache structure of AMD’s next-gen Bulldozer architecture. The document relates to Orochi – featuring four Bulldozer modules, or eight physical cores. Each module contains 2MB L2 cache shared between the two cores. 8MB L3 cache will be shared amongst all four modules. The total cache in the Bulldozer eight-core CPU is thus 16MB, compared to 9MB for Phenom II X6 CPUs. That is a 77% increase in cache despite only a 33% increase in core count.

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Xbitlabs have seen a document which reveals the cache structure of AMD’s
next-gen Bulldozer architecture. The document relates to Orochi -
featuring four Bulldozer modules, or eight physical cores. Each module
contains 2MB L2 cache shared between the two cores. 8MB L3 cache will be
shared amongst all four modules. The total cache in the Bulldozer
eight-core CPU is thus 16MB, compared to 9MB for Phenom II X6 CPUs. That
is a 77% increase in cache despite only a 33% increase in core count.

Higher cache per core is a general trend, with Intel upping cache sizes for its LGA2011 Sandy Bridge CPUs – Bulldozer’s purpoted competitor. However, Intel’s approach is different. While Bulldozer features 1MB L2 cache per core, Sandy Bridge retains Nehalem’s 256KB L2 cache per core. However, Sandy Bridge eight-core features a whopping 20MB of L3 cache – more than Bulldozer’s L2+L3 combined. Even Sandy Bridge six-core is expected to feature 15MB L3 cache (as opposed to 12MB for Gulftown).

Indeed, a 8MB L3 cache for Orochi is actually less L3 cache per core than Deneb / Phenom II X4. However, AMD believes in boosting the unified L2 module cache, perhaps to boost single core performance.

Of course, the relevance of the document Xbitlabs is quoting can be questioned – with AMD likely to have made changes since.

Bulldozer is still a long way away. Whilst official release date is still “2011″, a Q4 2011 is widely rumoured.

Reference: Xbitlabs