Before tweaks
=============
Standard installations, no intentional tweaks despite "UseDNS no". All
VMs run on the same host using KVM.
Arch Linux (openssh-6.8p1-2):
$ time for i in {1..100}; do ssh overqemu00 /bin/true; done
real 0m9.904s
user 0m1.300s
sys 0m0.123s
Ubuntu 12.04 (openssh-server-5.9p1-5ubuntu1.4):
$ time for i in {1..100}; do ssh overqemu01 /bin/true; done
real 0m34.388s
user 0m0.797s
sys 0m0.130s
Ubuntu 14.04 (openssh-server-6.6p1-2ubuntu2):
$ time for i in {1..100}; do ssh overqemu02 /bin/true; done
real 0m32.895s
user 0m1.340s
sys 0m0.133s
CentOS 7 (openssh-6.6.1p1-11.el7):
$ time for i in {1..100}; do ssh overqemu05 /bin/true; done
real 0m18.580s
user 0m1.093s
sys 0m0.133s
For further reference:
OpenBSD 5.6 (openssh-6.7):
$ time for i in {1..100}; do ssh overqemu03 /usr/bin/true; done
real 0m8.871s
user 0m1.293s
sys 0m0.113s
FreeBSD 10.1 (openssh-6.6.1p1):
$ time for i in {1..100}; do ssh overqemu04 /usr/bin/true; done
real 0m8.876s
user 0m1.483s
sys 0m0.200s
After tweaks
============
What has been changed?
- Cleared /etc/update-motd.d on Ubuntu. PAM runs all these scripts
on each login.
Ubuntu 12.04:
$ time for i in {1..100}; do ssh overqemu01 /bin/true; done
real 0m6.884s
user 0m0.850s
sys 0m0.170s
Ubuntu 14.04:
$ time for i in {1..100}; do ssh overqemu02 /bin/true; done
real 0m8.452s
user 0m1.490s
sys 0m0.187s