For Day 29 of the series, I will talk about AMD Turbo CORE technology. AMD Turbo CORE is a technology that was first introduced in the AMD Phenom II X4 desktop processor, but the way AMD implemented it in the Bulldozer family and Piledriver family of processors is greatly enhanced. AMD Turbo CORE is similar to Intel Turbo Boost technology in concept (although AMD claims that it works better). According to AMD:
AMD Turbo CORE is deterministic, governed by power draw, not temperature as other competing products are. This means that even in warmer climates you’ll be able to take advantage of that extra headroom if you choose. This helps ensure a max frequency is workload dependent, making it more consistent and repeatable
AMD Turbo CORE allows individual cores in the processor to speed up from the base clock speed up to the TDP level, automatically adding extra single-threaded performance for the processor. Conceptually, it is the opposite of AMD PowerNow! technology. Instead of trying to watch for usage patterns and lowering the processor core speed to try to reduce power consumption, Turbo CORE is watching the power consumption to see how high it can move the clock speed up.
This feature, which is new to AMD server processors, allows individual cores to use the extra power headroom between average and maximum power, turning it into more clock speed. Bulldozer implements a significantly more aggressive version of this capability than the AMD Phenom desktop processor. Should the processor get too close to the TDP power limit, it will automatically throttle back somewhat to ensure that it is continuing to operate within the specified TDP guidelines. This allows for significantly higher maximum clock speeds for the individual cores.
AMD has stated that Bulldozer will boost the clock speed of all 16 cores by 500MHz, even when all cores are active with server workloads. Even higher boost states available with half of the cores active, anywhere from 700Mhz to 900MHz. With the Bulldozer and Piledriver processors you see processors marketed with a base and a maximum frequency, base will reflect the actual clock speed on the processor and max will reflect the highest AMD Turbo CORE state.
Just like with Intel Turbo Boost technology, I think this is a very beneficial feature that you should take advantage of for database server usage. I don’t see any controversy here (such as with hyper-threading). Since Microsoft changed over to core-based licensing for SQL Server 2012, it is much less practical to choose an AMD processor (especially for an OLTP workload) because of their high physical core counts and low single-threaded performance.
One scenario where an AMD-based database server could make some sense would be for a dedicated OLAP server, using SQL Server 2012 Business Intelligence Edition, with server-based licensing. Having lots of physical cores without having to pay a huge amount for your SQL Server 2012 licenses is not a bad scenario.