GLibC

  1. Bug #2030515
  2. Comment #17

Comment 17 for bug 2030515

Revision history for this message
In , Adhemerval Zanella (adhemerval-zanella) wrote :

On Zen3 I am not seeing such slowdown using vectorized instructions. With a patch glibc to disable REP MOVSB I see:

$ ./testrun.sh ./memcpy_loop -D 512 -b 4096 -t mmap_huge -f memcpy -p 10000000
146.593 GB/s

# Force REP MOVSB
$ GLIBC_TUNABLES=glibc.cpu.x86_rep_movsb_stop_threshold=4097 ./testrun.sh ./memcpy_loop -D 512 -b 4096 -t mmap_huge -f memcpy -p 10000000
116.298 GB/s

And I don't see difference between mmap and mmap_huge.