On 15/02/03, Satish Chandra Kilaru wrote: > How many events can kernel accumulate without I/o ?
The kernel default is 64 *buffers*, but I think Fedora and RHEL set it to 320. It is now possible to set it to "0" which means limited only by system resources. See "man auditctl", "-b" option. An event can be made up of several buffers. Of course, how long a system lasts before the queue blows up depends on your rule set... However, at the moment, it will still write out to klog if auditd isn't running. > On Tuesday, February 3, 2015, Viswanath, Logeswari P (MCOU OSTL) < > logeswari...@hp.com> wrote: > > > I don't want to disable auditing (i.e. disable audit record collection), > > but just do not want the records to delivered to user space since I want to > > remove the I/O overhead while running the performance test. > > Is there any option for this? > > > > -----Original Message----- > > From: Richard Guy Briggs [mailto:r...@redhat.com <javascript:;>] > > Sent: Thursday, January 29, 2015 10:23 PM > > To: Viswanath, Logeswari P (MCOU OSTL) > > Cc: Satish Chandra Kilaru; Steve Grubb; linux-audit@redhat.com > > <javascript:;> > > Subject: Re: Linux audit performance impact > > > > On 15/01/29, Viswanath, Logeswari P (MCOU OSTL) wrote: > > > Please read my question as “Is there any option to configure kaudit > > > not to log audit records to syslog? when auditd not running.” > > > > Yeah, remove audit=1 from the kernel command line, or set audit=0 in its > > place. This will stop all but AVCs and if auditd has ever run since boot. > > If audit=0 is on the kernel boot line, it will be impossible to run auditd. > > > > There is a feature request that is likely coming soon that could be > > useful: > > > > https://bugzilla.redhat.com/show_bug.cgi?id=1160046 > > "If no audit daemon is running, but an audit multicast subscriber is > > around, then the kernel shouldn't forward audit data to kmsg" > > > > > From: Viswanath, Logeswari P (MCOU OSTL) > > > Sent: Thursday, January 29, 2015 11:49 AM > > > To: 'Satish Chandra Kilaru'; Steve Grubb > > > Cc: linux-audit@redhat.com <javascript:;> > > > Subject: RE: Linux audit performance impact > > > > > > Is there any option to configure kaudit not to log audit records to > > syslog when auditd is running? > > > This way we can assess the impact of enabling audit without involving > > disk I/o overhead. > > > > > > From: Satish Chandra Kilaru [mailto:iam.kil...@gmail.com <javascript:;>] > > > Sent: Thursday, January 29, 2015 9:12 AM > > > To: Steve Grubb > > > Cc: linux-audit@redhat.com <javascript:;><mailto:linux-audit@redhat.com > > <javascript:;>>; Viswanath, > > > Logeswari P (MCOU OSTL) > > > Subject: Re: Linux audit performance impact > > > > > > I agree with you... but writing to disk can trigger further events > > leading spiralling of events... > > > I brought down my server few times with stupid rules... > > > > > > On Wed, Jan 28, 2015 at 10:39 PM, Steve Grubb <sgr...@redhat.com > > <javascript:;><mailto:sgr...@redhat.com <javascript:;>>> wrote: > > > On Wednesday, January 28, 2015 10:18:47 AM Satish Chandra Kilaru wrote: > > > > Write your own program to receive audit events directly without > > > > using auditd... > > > > That should be faster .... > > > > Auditd will log the events to disk causing more I/o than u need... > > > > > > But even that is configurable in many ways. You can decide if you want > > > logging to disk or not and what kind of assurance that it made it to > > > disk and the priority of that audit daemon. Then you also have all the > > > normal tuning knobs for disk throughput that you would use for any > > > disk performance critical system. > > > > > > -Steve > > > > > > > On Wednesday, January 28, 2015, Viswanath, Logeswari P (MCOU OSTL) < > > > > > > > > logeswari...@hp.com <javascript:;><mailto:logeswari...@hp.com > > <javascript:;>>> wrote: > > > > > Hi Steve, > > > > > > > > > > I am Logeswari working for HP. > > > > > > > > > > > > > > > > > > > > We want to know audit performance impact on RHEL and Suse linux to > > > > > help us evaluate linux audit as data source for our host based IDS. > > > > > > > > > > When we ran our own performance test with a test audispd plugin, > > > > > we found if a system can perform 200000 open/close system calls > > > > > per second without auditing, system can perform only 3000 > > > > > open/close system calls auditing is enabled for open/close system > > > > > call which is a HUGE impact on the system performance. It would be > > > > > great if anyone can help us answering the following questions. > > > > > > > > > > > > > > > > > > > > 1) Is this performance impact expected? If yes, what is the > > reason > > > > > behind it and can we fix it? > > > > > > > > > > 2) Have anyone done any benchmarking for performance impact? If > > yes, > > > > > can you please share the numbers and also the steps/programs used > > > > > the run the same. > > > > > > > > > > 3) Help us validating the performance test we have done in our > > test > > > > > setup using the steps mentioned along with the results attached. > > > > > > > > > > > > > > > > > > > > Attached test program (loader.c) to invoke open and close system > > calls. > > > > > > > > > > Attached idskerndsp is the audispd plugin program. > > > > > > > > > > We used time command to determine how much time the system took to > > > > > complete 50000 open/close system calls without (results attached > > > > > Without-auditing) and with auditing enabled on the system > > > > > (With-auditing-NOLOG-audispd-plugin and With-auditing-RAW) > > > > > > > > > > > > > > > > > > > > System details: > > > > > > > > > > > > > > > > > > > > 1 CPU machine > > > > > > > > > > > > > > > > > > > > *OS Version* > > > > > > > > > > RHEL 6.5 > > > > > > > > > > > > > > > > > > > > *Kernel Version* > > > > > > > > > > uname –r > > > > > > > > > > 2.6.32-431.el6.x86_64 > > > > > > > > > > > > > > > > > > > > Note: auditd was occupying 35% of CPU and was sleeping for most of > > > > > the time whereas kauditd was occupying 20% of the CPU. > > > > > > > > > > > > > > > > > > > > Thanks & Regards, > > > > > > > > > > Logeswari. > > > > > > > > > > > > -- > > > Please Donate to www.wikipedia.org<http://www.wikipedia.org> > > > > > -- > > > Linux-audit mailing list > > > Linux-audit@redhat.com <javascript:;> > > > https://www.redhat.com/mailman/listinfo/linux-audit > > > > > > - RGB > > > > -- > > Richard Guy Briggs <rbri...@redhat.com <javascript:;>> > > Senior Software Engineer, Kernel Security, AMER ENG Base Operating > > Systems, Red Hat Remote, Ottawa, Canada > > Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545 > > > > > -- > Please Donate to www.wikipedia.org - RGB -- Richard Guy Briggs <rbri...@redhat.com> Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat Remote, Ottawa, Canada Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545 -- Linux-audit mailing list Linux-audit@redhat.com https://www.redhat.com/mailman/listinfo/linux-audit