Hi- It looks like 32-bit x86 Debian glibc doesn't use AT_SYSINFO. This kills syscall performance. Upstream glibc as well as Fedora's glibc work fine. This test: https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/commit/?h=x86/entry_compat&id=9d742073d4c0449b262dbe0a3dab4a7c1d831500 inadvertently found this issue. Any ideas? I'm only barely a Debian user -- I have a Debian-based test VM. --Andy (kernel vDSO maintainer)