heterogeneous Uniform Memory Access

Several years back we first heard AMD’s plans on creating a uniform memory architecture which will allow the CPU to share address spaces with the GPU.  The promise here is to create a very efficient architecture that will provide excellent performance in a mixed environment of serial and parallel programming loads.  When GPU computing came on the scene it was full of great promise.  The idea of a heavily parallel processing unit that will accelerate both integer and floating point workloads could be a potential gold mine in wide variety of applications.  Alas, the promise of the technology did not meet expectations when we have viewed the results so far.  There are many problems with combining serial and parallel workloads between CPUs and GPUs, and a lot of this has to do with very basic programming and the communication of data between two separate memory pools.

CPUs and GPUs do not share common memory pools.  Instead of using pointers in programming to tell each individual unit where data is stored in memory, the current implementation of GPU computing requires the CPU to write the contents of that address to the standalone memory pool of the GPU.  This is time consuming and wastes cycles.  It also increases programming complexity to be able to adjust to such situations.  Typically only very advanced programmers with a lot of expertise in this subject could program effective operations to take these limitations into consideration.  The lack of unified memory between CPU and GPU has hindered the adoption of the technology for a lot of applications which could potentially use the massively parallel processing capabilities of a GPU.

The idea for GPU compute has been around for a long time (comparatively).  I still remember getting very excited about the idea of using a high end video card along with a card like the old GeForce 6600 GT to be a coprocessor which would handle heavy math operations and PhysX.  That particular plan never quite came to fruition, but the idea was planted years before the actual introduction of modern DX9/10/11 hardware.  It seems as if this step with hUMA could actually provide a great amount of impetus to implement a wide range of applications which can actively utilize the GPU portion of an APU.

Click here to continue reading about AMD's hUMA architecture.

Moving Towards BGA Only?

The sky is falling.  Does this mean that Chicken Little is panicking for no reason or is Chicken Little the Cassandra of our time?  It has been widely reported that Intel will not be offering the next generation Broadwell architecture as a LGA based product.  Broadwell is a 14 nm product that will integrate southbridge functions into the chip, making it essentially a SOC.  It will be offered only as a BGA only product, which means that it will be soldered onto a motherboard with no chance of being able to be swapped out.  Broadwell is the successor to the upcoming Haswell, itself a 22 nm product that features many architectural changes to both the CPU and graphics portion as compared to the current 22 nm Ivy Bridge.

Will Broadwell be the death of the desktop industry and enthusiasts?  Will LGA become as scarce as chicken teeth?  Will we ever see a product with a swappable CPU after 2014?

Broadwell is aimed at TDPs ranging from 10 watts to 57 watts.  Current high end Ivy Bridge parts max out at 77 watts and do not feature any southbridge type functionality.  So that means that another 5 to 7 watts are added in for the chipset when discussing basic system TDPs.  So we are looking at around 87 watts for a top end product when including SATA and USB functionality.  30 watts is a pretty big deal in OEM circles.  We see right off the bat that Intel is aiming this architecture at a slightly different market, or at least a changing marketplace.

The unease that we are seeing is essentially this; Intel appears to be trying to take more profits from this setup and pass more costs onto the motherboard industry.  This is not necessarily new for Intel, as they did this when transitioning to the LGA socket.  LGA sockets are more expensive and more troublesome for the motherboard manufacturers as compared to a more traditional pin based interface.  AMD continues to use pin based chips as this lowers the cost that is incurred by the motherboard manufacturers, and it also lowers overall support issues.  LGAs are pretty solid, but it is very easy to bend one or more of those contacts so that they in fact do not create a solid connection with the CPU.  This is something that is uncommon with pin based CPUS, but the downside of pin based is that it is more expensive to produce the CPU in the first place as compared to a LGA chip which only features the pads on the substrate of the CPU.

Continue reading our thoughts on Intel's move to BGA processors...

Bulldozer to Vishera

Bulldozer is the word.  Ok, perhaps it is not “the” word, but it is “a” word.  When AMD let that little codename slip some years back, AMD enthusiasts and tech journalists started to salivate about the possibilities.  Here was a unique and very new architecture that promised excellent single thread performance and outstanding multi-threaded performance all in a package that was easy to swallow and digest.  Probiotics for the PC.  Some could argue that the end product for Bulldozer and probiotics are the same, but I am not overly fond of writing articles containing four letter colorful metaphors.

The long and short of Bulldozer is that it was a product that was pushed out too fast, it had specifications that were too aggressive for the time, and it never delivered on the promise of the architecture.  Logically there are some very good reasons behind the architecture, but implementing these ideas into a successful product is another story altogether.  The chip was never able to reach the GHz range it was supposed to and stay within reasonable TDP limits.  To get the chip out in a timely manner, timings had to be loosened internally so the chip could even run.  Performance per clock was pretty dismal, and the top end FX-8150 was only marginally faster than the previous top end Phenom II X6 1100T.  In some cases, the X6 was still faster and a more competent “all around” processor.

There really was not a whole lot for AMD to do about the situation.  It had to have a new product, and it just did not turn out as nicely as they had hoped.  The reasons for this are legion, but simply put AMD is competing with a company that is over ten times the size, with the resulting R&D budgets that such a size (and margins) can afford.  Engineers looking for work are a dime a dozen, and Intel can hire as many as they need.  So, instead of respinning Bulldozer ad nauseum and releasing new speed grades throughout the year by tweaking the process and metal layer design, AMD let the product line sit and stagnate at the top end for a year (though they did release higher TDP models based on the dual module FX-4000 and triple module FX-6000 series).  Engineers were pushed into more forward looking projects.  One of these is Vishera.

Click here to read the rest of the Vishera Review!

Trinity Finally Comes to the Desktop

Trinity.  Where to start?  I find myself asking that question, as the road to this release is somewhat tortuous.  Trinity, as a product code name, came around in early 2011.  The first working silicon was shown that Summer.  The first actual release of product was the mobile part in late Spring of this year.  Throughout the summer notebook designs based on Trinity started to trickle out.  Today we cover the release of the desktop versions of this product.

AMD has certainly had its ups and downs when it comes to APU releases.  Their first real APU was Zacate, based on the new Bobcat CPU architecture.  This product was an unmitigated success for AMD.  Llano, on the other hand, had a pretty rocky start.  Production and various supply issues caused it to be far less of a success than hoped.  These issues were oddly enough not cleared up until late Spring of this year.  By then mobile Trinity was out and people were looking towards the desktop version of the chip.  AMD saw the situation, and the massive supply of Llano chips that it had, and decided to delay introduction of desktop Trinity until a later date.

To say that expectations for Trinity are high is an understatement.  AMD has been on the ropes for quite a few years in terms of CPU performance.  While the Phenom II series were at least competitive with the Core 2 Duo and Quad chips, they did not match up well against the latest i7/i5/i3 series of parts.  Bulldozer was supposed to erase the processor advantage Intel had, but it came out of the oven as a seemingly half baked part.  Piledriver was designed to succeed Bulldozer, and is supposed to shore up the architecture to make it more competitive.  Piledriver is the basis of Trinity.  Piledriver does sport significant improvements in clockspeed, power consumption, and IPC (instructions per clock).  People are hopeful that Trinity would be able to match the performance of current Ivy Bridge processors from Intel, or at least get close.

So does it match Intel?  In ways, I suppose.  How much better is it than Bulldozer?  That particular answer is actually a bit surprising.  Is it really that much of a step above Llano?  Yet another somewhat surprising answer for that particular question.  Make no mistake, Trinity for desktop is a major launch for AMD, and their continued existence as a CPU manufacturer depends heavily on this part.

Continue reading our review of the AMD Trinity A10 APUs!!