Hacker News Reader

I’m confused- they are claiming same compute for same cost but mainframe is 1 30 core chip and HP is 12x 24 core chips. Hard to believe ibm has a chip 10x faster per core

View on HN

There are some relevant architectural differences that explain that. Most fundamental is that the Z CPUs can run continuously at 5.2GHz. Another difference is that these CPUs are assisted by a multitude of smart IO devices, each its own computer, that offload almost everything but application code off the CPUs. They also have humongous caches and will not wait for main memory as often as x86's.

IBM claims 7x better per-core performance vs x86, but they're lying about that, of course.

Overall, yes, I have difficulty believing that number. For a subset of common workloads, it might actually be true, though.

IBM does some crazy stuff with hardware acceleration and specialized units that take load off of the actual CPUs.

I tried out hardware accelerated compression on a z15 and it just speeds it up a stupid amount, something like 20x times in decompression and 200 times with compression [0], which is not something that is done many other places yet. Though the PlayStation 5 does have it [1]

[0]: https://github.com/rust-lang/libz-sys/pull/72#issuecomment-9...

[1]: http://cbloomrants.blogspot.com/2020/09/how-oodle-kraken-and...

Reply on news.ycombinator.com