AMD Announces the Availability of 64-bit ARM Opteron Developer Kits

By the time this hardware is widely available, all your favourite Linux distros will Just Work, with ~99% of the functionality/packages/languages of x86. In fact that's pretty much the case already.

But in general, why Xen over KVM? the primary reason is that I understand xen better.

I have a secondary reason, and it's a long-term bet against KVM.

KVM has a lot of features that while they are interesting in the corporate space, make oversubscription too easy in the hosting space. Set up a KVM host with a bunch of ram and a bunch of swap, and start handing out "memory" to your kvm guests? By default it will get ram or swap as availability and usage dictate, just like any other process.

To be absolutely clear, as far as I can tell, none of the current KVM VPS providers are using these over-subscription methods right now. I'm not accusing anyone of anything.

However, the primary reason why Xen beat OpenVZ and the other containerization systems was that it is really quite difficult to oversubscribe ram on a Xen host, and your pagecache was in your ram. It was not shared with others.

Sure, if the manager of an OpenVZ host allocates resources responsibly, it can be more efficient than Xen. And some hosts did that. But, because some hosts did not do that, Xen developed a reputation. Buy a xen host, and you are getting honest ram. Buy an OpenVZ host and you are relying on the reputation of the host.

KVM, now, can be configured to run in the same way Xen is, with no sharing of memory, pagecache or otherwise.

However, it is simple to give KVM guests memory that is ram /or/ swap, and other than performance, it would be impossible to tell, from the guest, what I gave you.

Now, of course, right now KVM enjoys the same reputation as Xen, because all the current KVM providers seem to be doing the responsible thing and only handing out ram, not ram/swap mix, but at some point? someone is going to change that.

The irritating thing is that the xen developers seem to be running as hard as they can to put in kvm-stlye features to share more memory. Isolation, when you are in a multi-tenant environment, is often more important than overall efficiency.

Too bad it wasn't competitively priced.

Well, that and the fact that the memory is soldered on in most cases and the total device cost extremely low (compared to servers). So you are expected to simply replace your system entirely in the event that there are memory errors you notice. And hopefully nothing goes wrong that you don't notice.

Also, I suppose technically if you were only worried about bit flips due to solar activity, then a tiny amount of RAM on a tiny chip has less surface area and fewer bits TO flip than your standard full sized DIMM.

This is a dev kit not a commercial offering...

Of course they'll tend to pick cases where it helps a lot, but they claimed 50% wall time and 25% power savings on a Hadoop job, and they emulate the zlib API.

If I'm reading right this was with a Sandy Bridge-based Xeon; time saved by the coprocessor could be greater when the CPU is slower.

Really interesting--thanks for the pointer.

ARM's sweet spot has traditionally been for CPUs that are otherwise going to be underutilized, saving both power and CPU costs in those circumstances. As cloud platforms become better at ensuring maximum utilization of CPUs, and a larger portion of workloads become throughput intensive, it moves things a bit more in Intel's direction. ARM will probably find a better market in the Internet of Things than in the data center.

Maybe this is what you're alluding to, but Intel used a whole host of anti-competitive practices to prevent AMD from gaining a foothold in the market at a time when AMD had faster and better CPUs. And this was part of the reason why AMD ended up buying ATI (IIRC they were after NVIDIA for a while) - they wanted another angle from which to attack Intel.

But it seems like they overpaid for ATI, and then Barcelona happened and Bulldozer was delayed beyond belief and so the last few years have been very tough for AMD. Let's hope this gets them back into the game.

For example, in less than a year Intel will be selling a Xeon socket compatible chip with 72 Atom cores with the same power envelope as a normal Xeon server chip. And each core will have two 512-bit vector pipelines (AVX3?), so the throughput for compute intensive operations should be impressive. It will undoubtedly be expensive but if you look at the overall dollars per compute, and how many VMs and similar you could run on it simultaneously, it starts to look very attractive in terms of data center economics.

That's pretty stupid considering all A-series APUs they've been selling for a few years now.