You seem very insightful on this topic. May I ask your opinion as to why ARM is taking off on the server market?
When you're running commercial software at $$$$ per license, the customers basically have to stick to whatever hardware is explicitly supported. And the vendors are going to be narrow there. Fewer platforms keep support costs down, and prevent exposure to uncompetitive corners of the market. As long as $expensive_product is only officially supported for x86, nobody needs to know it's riotously unperformant on ARM in ways that will require wholesale rewrites to fix.
When it's all open stuff, nothing stops people from compiling it for ARM, RISC-V, and hell 65C816, letting the market choose which platform fits their needs best. For many audiences it might not be "maximum performance under cost-no-object hardware"; it might be "what's the cheapest way to serve a fixed N workload units per month, when you include the purchase cost, electricity cost, rack-space rental cost, etc."
As a second-order effect, I expect removing license cost from the equation also impacts the metrics people care about. When the software price is the dominant aspect of the bill, nobody's going to make much of a case of "we can save 55 of the annual cost up front by using cheaper good-enough hardware" or "we'll save 1% per month on the energy bill".
Many people don’t realize ARM can trace its origins back to the BBC Micro. For a variety of reasons it found a niche in low power applications, even 30+ years ago. ARM, the company, simply sells licenses without producing its own silicon. There’s concern now with it going public that it will seek revenue by jacking up licensing costs.
It’s mobile devices where ARM flourished and entered public consciousness. There used to be other platforms but they died off. Intel sold XScale years ago because of a lack of vision.
ARM processors got sufficiently powerful to be in servers and power efficiency became a big deal. Google really transformed this space with sub-1.1 PUEs when no one outside even believed that was possible. Performance per Watt became a really big deal.
Also, I’m not sure if this is entirely fair but I credit Apple with a lot of ARM’s success. They bought a company called PA Semi and pushed the envelope with what ARM can do. I think that may have been the best $400 million (IIRC) ever spent.
This makes it sound as if xscale was an alternative platform to ARM. Intel xscale cores implemented the ARMv5 isa.
AArch64 and AMD64 has more in common than Itanium which is a bag of hurt from hardware to compiler.
ARM on Server actually saves money at the scale being deployed, while Itanium has zero cost advantage, and that is before adding the cost of software which was order of magnitude worst than any estimate had made at the time.
Most Server software operate on Open Source software. From Linux to Nginx, MySQL, Postgres, Memcache or Redis and tons and tons OSS. Which makes changes far easier than waiting for vendor to support AArch64.
AArach64 has a much bigger market to fine tune its software stack and toolchain from Smartphones. There are currently 4.5+Billion of Smartphone in uses, that is larger than all the x86 usage in the world. Compare that to IA64 /Itanium.
So for a few HPC type things, it was an a leap forward, for everything else, it sucked.
It was like the arm based windows surface laptops a few years ago. Lots of promise, none of the software that you actually wanted.
When you looked at the opteron which was 64 bit, run faster, cheaper than the intel and could run vanilla 32bit apps without any changes faster than before, it was a no brainer.
Starting a CPU company and selling CPUs to customers has always been difficult since you need to compete with other CPU packagers and Intel had the largest scale so could always put you out of business if you became a threat.
With the rise of big cloud server giants (AWS, Azure, Google), they can license the cores from ARM, build their own CPUs and cut out the middle-man. They are their own CPU customers so don't have to worry about building a market.
It's the rise of vertical integration from tech giants.
ARM is cheaper and the performance hit is smaller than the savings. For scalable workloads you can easily just run more ARM and save money. Also, a lot (lot) of workloads are memory or I/O bound so the performance hit is negligible. ARM has gotten pretty optimized in both the CPU architecture and the tooling thanks to mobile uses.
What AWS offers and what Google offers are not even close: on AWS, our workloads actually perform better (as in, higher QPS/core, resulting in fewer pods/instances), in addition to being more cost effective (both in terms of per-instance price to begging with, and less instances in total, due to aforementioned higher QPS/core serving same amount of total requests). For the limited ARM offer from Google we tested, the performance is worse than equivalent x86 instances, in addition to no price incentives.
It's pretty funny.
> with the characteristics of the processor architecture nor with processor performance.
Why did AMD introduce Genoa and Intel is developing equivalent products too? There is market for CPUs with a very high number of low-powers cores and it seems ARM had an advantage there. Even now the price per core (which are good enough for many applications) for Ampere/Gravitron cores is significantly lower.