Audit / Netlink slowness

[Bernardo Innocenti]

Hello,

on a server running kernel 2.6.11-1.1369_FC4, both ssh
and su where taking a longish amount of time (over >1.5 sec.)

Running "strace -r 2>strace.out su", I discovered that
netlink communication is the major cause of slowdown.

"su" connects to a NETLINK_AUDIT socket 3 or 4 times.
Each time it does 2 sendto() + recvfrom() operations,
with a latency of ~200ms.  This adds up to 800ms wasted
time.

Disabling CONFIG_AUDIT in the kernel makes su and ssh
very fast again.

Is this behavior to be expected?  CONFIG_AUDIT is enabled
by default, therefore many people are going to be hit by
this problem.

-- 
  // Bernardo Innocenti - Develer S.r.l., R&D dept.
\X/  http://www.develer.com/