AMD QuadFX Platform and FX-70 Series Launched

MojoKid writes, "AMD officially launched their QuadFX platform and FX-70 series processors today, previously known as 4x4. FX-70 series processors will be sold in matched pairs at speeds of 2.6, 2.8, and 3GHz. These chips are currently supported by NVIDIA nForce 680a chipset-based, dual-socket motherboards, namely the Asus L1N64-SLI WS, which is currently the only model available. HotHardware took a fully configured AMD QuadFX system out for a spin and though performance was impressive, the fastest 3GHz quad-core FX-74 configuration couldn't catch Intel's Core 2 Extreme QX6700 quad-core chip in any of the benchmarks. The platform does show promise for the future, however, especially with AMD's Torenzza open socket initiative." And mikemuch writes that the QuadFX "not only fails to take the performance crown from Intel's quad-core Core 2 Extreme QX6700, but in the process burns almost twice as much electricity and runs significantly hotter in the process. ExtremeTech has a plethora of application and synthetic benchmarks on QuadFX, including gaming and media-encoding tests."

Comments

Re:AMD's new Power HOG

[fitten]

Intel's got a shared L2 that's 2-4 times the size of the AMD equivalents' pool.
AMD's got a coherent, but NON-shared L2 split across multiple CPUs- each core has it's own L2. You'll have less L2 thrash with that design.

Under an SMP load, the AMD design will have an edge if all four cores are busy in different parts of system memory.
If you pop out of cache, the memory bus design and overall architecture of the AMD parts will have an edge.

In CPU architecture circles, the shared L2 is considered a more ideal design than split L2 for multi-core processors. There are plenty of talks around the 'net as to why.

As far as cache size, that's a design tradeoff just like any other. Because of the slowness of main memory, you want to have as large a cache system as possible. However, cache system latency increases with the size of the cache so that is a tradeoff as well. Intel chose to use some chip realestate for cache. "Faulting" them for this is just being an apologist for your puppy.

There are many types of "SMP loads". Multi-threaded loads where all threads work on the same data will be similar on both as there is only one pipe to the memory on both the NUMA and the FSB model, for example. But yet, on SMP loads that are more 'lose', you can get good benefits from NUMA. By the way, Intel also has the IMC with their equivalent to HT on the roadmaps, so this discussion (NUMA vs FSB) won't be relevant for much longer.

Additionally, it isn't until AMD's 'next thing' where their NUMA architecture will be able to scale much better (it doesn't do that well with lots of sockets because it falls back to being limited by the number of HT connections so some communication has to be multi-jump with current multi-socket solutions - the new core adds an HT link so that 4+ sockets can have a more direct path around the system).

There are a number of examples of "popping out of cache" in the tests on various sites. AMD does show that it helps in those when it can use the bandwidth of both NUMA branches but it isn't convincingly better than Intel's FSB on many/any of the tests that are shown (you'd hope to see idealistically 2x performance improvement on many of those, but even with all the extra bandwidth, AMD doesn't seem to 'blow the doors' off of the Intel parts... in fact, AMD doesn't even beat them even with the added bandwidth... this just shows that there may be more to the picture than an IMC + more bandwidth). Even AMD's latency isn't that much better than Intel's FSB design anymore (the nice advantage that had against NetBurst is pretty much gone).

I'm eagerly awaiting AMD's next 'real' move, myself, but given that Intel is already sampling 45nm parts and even on 65nm Core is able to clock to 3.5GHz ranges (meaning Intel has a lot of headroom even on 65nm), the short amount of time that Intel and AMD will overlap on 65nm will probably just show equality (at best) between the two. I haven't really seen what performance advantages AMD's new features give, other than the obvious benefits of wider paths and the FPU issue increase (to bring it equal to Intel's issue rate, although AMD has typically had a stronger FPU). AMD claims a lot, but that could simply be marketing at this point.

Re:Quad cores - great for servers... but.

[N7DR]

Well, having lived with an AMD 64x2 for over a year now, I feel comfortable saying that a dual core proc is pretty useless to me. I've noticed absolutely no difference in my computing experience, either in the newest games or in day-to-day non-game activity. It's no different than my similarly clocked A64 with one core.

Stating the blindingly obvious: some people aren't going to notice much (if any) difference; others are going to see a huge difference. Parent falls into the former camp; I fall into the latter. I also have been using 62x2 for a year, and no way would I go back to single core. It would be worth having dual core if only for the fact that I can start a job and it will consume a core while all my interactive work runs on the second core, and hence I don't even notice that a huge job is running in the background. Everything else one gets with dual-core is an added bonus. I'm not totally certain that going to 4 cores on the desktop will be as useful, but I can believe that it might be, and will certainly be worth trying. For me, anyway (and I can't believe that I'm particularly untypical of slashdot users).

Given my experience, I'm even fairly convinced that the rest of my family (who are much more like ordinary users) would benefit from dual core too. Everything is simply so much more responsive.

Re:Windows XP NUMA support

[kscguru]

Having done NUMA benchmarks ... on AMD chips, certain workloads take a latency hit from 60ns / memory access to 80ns / memory access. Bandwidth is halved. Net, it's a 5-10% slowdown across all workloads (5% if you try for average-case performance, 10% if you just hope for the best). Both sites point out that it is NUMA making the difference, yet both sites insisted on staying with Windows XP. A new motherboard like that, it's defaulted for a NUMA OS, so this is the 10% realm. As you point out, it would be extremely simple to run modern Linux (or Windows 2003, or Windows XP x64, or Vista) and see how well a NUMA scheduler works. (Note to Linux fans: Linux didn't have good NUMA scheduling either when Windows XP came out. A fair comparison would be against Linux 2.4.3 or so). This benchmark is fantastically stupid - it's the equivalent of running game benchmarks with a Voodoo3 graphics card to see CPU differences, determining that the graphics card is the bottleneck, then claiming one CPU is faster! Their benchmarks exposed a major slowdown in the memory system, easily corrected with an OS upgrade, and they refused to correct it.

In short, once you factor NUMA out of these benchmarks, the difference between AMD quad and Intel quad is approximately the same as the difference between AMD's K8 arch and Intel's Core arch for single cores. Umm... duh?