Thanks again black_zion. But how does the P1 'all core boost' state make any sense if the TDP is too low to use it? Everywhere I read that all cores can be boosted to 2.1GHz simultanously, but in real life this can never happen??
For example see http://blogs.amd.com/work/2011/11/16/a-big-boost/
It depends on how hard the cores are used, as some programs will hammer it harder than others, same way a power virus will push a CPU or GPU harder than a real world program, it all depends on if there is any thermal headroom left.
I'd say it's unlikely and when it does happen it's probably not all that useful. If all the cores of your CPU are active, but without enough work being done to jack up power dissipation, then increasing clock speed and doing it faster won't get you much in return. That this can happen at all is probably just a side effect of having per-core granularity in power gating. The earlier versions of turbo core didn't have that, so it was more of an "all or nothing" kind of choice, and there were limits to how aggressive the decisions made could be when switching states. Trying to boil all that down into some kind of easily digestible sound byte isn't always doable, and often leads to confusion like this.
Widgets like turbo core are best for lightly threaded workloads where there's potential for the chip to work hard on something, and yet still have some TDP space left over. It just happens to work out as a kind of patch to help with the relatively weak single threaded performance of Bulldozer as well, although I expect it'll stick around even after that gets sorted out.
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Best analogy I can think of is to think of TurboCore as HyperThreading. Under a weakly threaded load, which is much more common to the home and office market than server market, you'll see a performance boost, but under something which is heavily threaded and uses every core it's just not going to have an effect. The difference is that on desktops you can use AMD Overdrive to fiddle around with the TurboCore settings, raise the limits and such if you have aftermarket cooling. But there really is no substitute for full time higher clocks, but even then over the next 5-10 years the CPU is going to take on much less importance as GPUs, using OpenCL or other GPU programming languages, take on the heavier workloads, as a single upper mid range graphics card can gap a 4U server in terms of GFLOPS and IOPS performance.
But even with higher clocks, even at 4ghz compared to stock 3.4ghz with me, converting a 2 hour VOB to WMV or converting a few thousand pictures from RAW to JPEG or even playing games (granted this is because I play at a more GPU limited than CPU limited resolution), the performance difference are negligible.
We will use this server as KVM host. With most KVM's (virtual machines) bound to one or two CPU cores, Turbo Core can be very usefull. Most KVM's are not very busy, so the TDP allows to boost the few busy KVM's quite a lot.
Originally posted by: MimeIf all the cores of your CPU are active, but without enough work being done to jack up power dissipation, then increasing clock speed and doing it faster won't get you much in return.
That's a very clever comment. The possibility to boost only a few cores while others are idle is much more useful (for weakly threaded applications/setups).