On 15/02/03, Satish Chandra Kilaru wrote: > Thanks for The info. But my question was rhetorical... I meant to say that > it would not be much... She is trying to bombard the system with open calls > ... So lots and lots of events will be generated and kernel has to write > down the events some where or discard them...
Exactly. It is of little practical use. You have to do I/O at some point, either to the same disk or another, or to a network interface or serial port, otherwise, just chuck it out. You could do a performance measurement on a short burst, then drain the queue, but what will that actually tell us? > On Tuesday, February 3, 2015, Richard Guy Briggs <[email protected]> wrote: > > > 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) < > > > [email protected] <javascript:;>> 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:[email protected] <javascript:;> > > <javascript:;>] > > > > Sent: Thursday, January 29, 2015 10:23 PM > > > > To: Viswanath, Logeswari P (MCOU OSTL) > > > > Cc: Satish Chandra Kilaru; Steve Grubb; [email protected] > > <javascript:;> > > > > <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: [email protected] <javascript:;> <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:[email protected] > > <javascript:;> <javascript:;>] > > > > > Sent: Thursday, January 29, 2015 9:12 AM > > > > > To: Steve Grubb > > > > > Cc: [email protected] <javascript:;> <javascript:;><mailto: > > [email protected] <javascript:;> > > > > <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 <[email protected] > > <javascript:;> > > > > <javascript:;><mailto:[email protected] <javascript:;> > > <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) > > < > > > > > > > > > > > > [email protected] <javascript:;> <javascript:;><mailto: > > [email protected] <javascript:;> > > > > <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 > > > > > [email protected] <javascript:;> <javascript:;> > > > > > https://www.redhat.com/mailman/listinfo/linux-audit > > > > > > > > > > > > - RGB > > > > > > > > -- > > > > Richard Guy Briggs <[email protected] <javascript:;> <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 <[email protected] <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 <[email protected]> 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 [email protected] https://www.redhat.com/mailman/listinfo/linux-audit
