I've noticed quite some drop of performance (around 15% in some cases) where
execution of lvm2 tests took longer time - and while tests itself should not
really load CPU system - the overall running time just got bigger.
Running bisect game pointed clearly to this commit:
Author: Al Viro <v...@zeniv.linux.org.uk>
Date: Thu Oct 5 12:59:44 2017 -0400
dev_ioctl(): move copyin/copyout to callers
clear revert of this commit on top of 3266b5bd97eaa72793df0b6e5a106c69ccc166c4
(recent ~4.16-rc4) restored timing of tests back.
I'm not sure why - so at this moment this is just a patch causing 15% longer
running times on lvm2 test suite.