On 06/08, Eric Paris wrote: > > On Wed, 2011-06-08 at 18:36 +0200, Oleg Nesterov wrote: > > And I guess, all CONFIG_AUDITSYSCALL code in entry.S is only needed to > > microoptimize the case when TIF_SYSCALL_AUDIT is the only reason for the > > slow path. I wonder if it really makes the measureble difference... > > All I know is what Roland put in the changelog: > > Avoiding the iret return path when syscall audit is enabled helps > performance a lot. > > I believe this was a result of Fedora starting auditd by default and > then Linus bitching about how slow a null syscall in a tight loop was. > It was an optimization for a microbenchmark. How much it affects things > on a real syscall that does real work is probably going to be determined > by how much work is done in the syscall. and probably by how much work is done in audit_syscall_entry/exit. OK. Thanks a lot Eric for your explanations. Oleg.
