Comment 20 for bug 1928508

Validated glibc from focal-proposed according to test case from description:

halves@glibc-zen:~$ ./test_memcpy64 32
32 MB = 1.222535 ms
-Compare match (should be zero): 0

halves@glibc-zen:~$ dpkg -l | grep libc-bin
ii libc-bin 2.31-0ubuntu9.9 amd64 GNU C Library: Binaries
halves@glibc-zen:~$ grep -m1 "model name" /proc/cpuinfo
model name : AMD Ryzen 7 3700X 8-Core Processor

Also validated on an Intel system, and no performance regressions have been observed:
halves@halves-focal-glibc-xeon:~$ ./test_memcpy64 32
32 MB = 2.174005 ms
-Compare match (should be zero): 0

halves@halves-focal-glibc-xeon:~$ grep -m1 "model name" /proc/cpuinfo
model name : Intel(R) Xeon(R) CPU E5-2683 v3 @ 2.00GHz
halves@halves-focal-glibc-xeon:~$ dpkg -l | grep libc-bin
ii libc-bin 2.31-0ubuntu9.9 amd64 GNU C Library: Binaries