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I have to strongly disagree with Linus here. While he got the history up to this point right, in the present it is very easy to develop for multiple platforms a

I have to strongly disagree with Linus here. While he got the history up to this point right, in the present it is very easy to develop for multiple platforms at once. CI platforms make it super easy. Cloudflare made a big effort to make all software run on x86 and aarch64, and it wasn't that hard at all. Most things today work out of the box. Many things that don't work, were not very robust to begin with, and fixing them to work on both platforms only made the software better as a whole. Cloudflare could move to ARM servers in a days' notice, and would already do that if Qualcomm hasn't closed the Centriq shop. The only real advantage I see for Intel today is AVX512, which can't be beat for some workloads, SVE would be able to compete for some workloads, but not all. However most workloads don't use vector processing instructions anyway. Still, I hope ARM improves their SIMD architecture further. As for the ALU performance difference, it is very easy to bridge. As evident by Apple's CPUs and Qualcomm Centriq simply having four ALU units gets you to about the same ALU performance as Intel. Branch prediction, cache performance and the interconnect are still much better at Intel processors. However Intel already peaked branch prediction performance, so the difference can only get smaller with time.

jlouis 8y ago
The CI angle was my first bet as well. You build and test in the cloud nowadays. Heck, you might develop on MacOS, and deploy on Linux. There are places where it matter, SIMD processing for instance, or low-level kernel development. But if you are on any kind of VM system, or ecosystem with a good compiler history, you are likely to have a smooth ride. If, in addition, the price point of the ARM machines are at 2/3 of the X86-64 ones, you are in trouble. x86 had another important point up its sleeve: price. And I might expect this was a confounding variable in Linus argument. Not only did you have the x86 at home. It was also like 1/8th of the price of an Alpha, PA-RISC or Sparc machine in price point. And at the time, x86 was dog slow compared to Alpha, and its I/O was laughable compared to HPPA/Sun. If you have a sizeable invoice at AWS, and you can shave the EC2 price by 2/3rds, you are going to have a lot of wiggle room to make sure your system runs on that aarch64.

jlouis 8y ago

The CI angle was my first bet as well. You build and test in the cloud nowadays. Heck, you might develop on MacOS, and deploy on Linux. There are places where it matter, SIMD processing for instance, or low-level kernel development. But if you are on any kind of VM system, or ecosystem with a good compiler history, you are likely to have a smooth ride. If, in addition, the price point of the ARM machines are at 2/3 of the X86-64 ones, you are in trouble. x86 had another important point up its sleeve: price. And I might expect this was a confounding variable in Linus argument. Not only did you have the x86 at home. It was also like 1/8th of the price of an Alpha, PA-RISC or Sparc machine in price point. And at the time, x86 was dog slow compared to Alpha, and its I/O was laughable compared to HPPA/Sun. If you have a sizeable invoice at AWS, and you can shave the EC2 price by 2/3rds, you are going to have a lot of wiggle room to make sure your system runs on that aarch64.