AMD's "Bulldozer" microarchitecture has been something of a disappointment, particularly in the FX desktop processors, where it doesn't consistently outperform AMD's prior-generation Phenom II chips. Since Bulldozer is the first full refresh of AMD's primary x86 architecture in many years, we've been left with lots of questions about why, exactly, the new microarchitecture hasn't performed up to expectations.
There are some obvious contributors, including lower-than-expected clock speeds and thread scheduling problems. Then again, using the Microsoft patches for Bulldozer scheduling didn't seem to help much during the testing for our Ivy Bridge review.
Some folks have speculated about one or two very specific problems with Bulldozer chips—such as relatively high cache latencies—being the culprit, which offered hope for a quick fix. However, the host of improvements AMD made to the "Piledriver" cores in its Trinity APU only offered gains of 1% or less each in per-clock instruction throughput, yielding relatively modest progress overall. There was no one, big change that fixed everything.
Now, Johan DeGelas has shed a little more light on the Bulldozer mystery with a careful analysis of Opteron performance in various server-oriented workloads, and his take is very much worth reading. He offers some intriguing possible reasons for Bulldozer's weak performance in certain scenarios, and those reasons aren't just cache latencies. Instead, he pinpoints this architecture's inability to hide its branch misprediction penalty, the low associativity of the L1 instruction cache, and—yep—a focus on server workloads as the most likely problem areas. There is hope for future IPC improvements, but some of those will have to happen in the generation beyond Piledriver, whose outlines we already know.
|Cooler Master's MasterCase Pro 6 reviewed||1|
|HTC Vive price permanently drops to $599||0|
|Acer Nitro 5 Spin boards the eighth-gen Core train||1|
|Eighth-gen Core desktop CPUs pack six cores and need new mobos||21|
|Intel kicks off eighth-gen Core with four cores and eight threads in 15W||47|
|Asus Vivobook Pro N580VD-DB74T can do offices and kids' parties||15|
|AMD's Ryzen Threadripper 1920X and Ryzen Threadripper 1950X CPUs reviewed||113|
|Thermaltake View 71 flaunts its glass on all angles||8|
|Deals of the week: mobos, CPUs, displays, and more||7|
|Somewhere in a dark office in the US where almost everyone has left for the weekend sits a tall man in his cubicle, glaring at his computer monitor in...||+18|