Very interesting. It might be the case that zstd optimizes more for recent machines; zstd famously uses four different compression streams to maximize instruction-level parallelism and that might not work well in older machines. I haven't seen any machine where zstd is significantly slower than it should, but those machines I could test came from 2013 or later. Or either the RHEL package might have been optimized for recent machines. It would be interesting to test a binary optimized for the current machine (-march=native -mtune=native).
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Using stock RHEL7/EPEL packages: zstd-1.5.0-1.el7.x86_64 On an old Athlon II X4 615e right now.
The difference in our results certainly is curious.
Very interesting. It might be the case that zstd optimizes more for recent machines; zstd famously uses four different compression streams to maximize instruction-level parallelism and that might not work well in older machines. I haven't seen any machine where zstd is significantly slower than it should, but those machines I could test came from 2013 or later. Or either the RHEL package might have been optimized for recent machines. It would be interesting to test a binary optimized for the current machine (-march=native -mtune=native).