Snort mailing list archives
Re: Pin snort single processor
From: Will Metcalf <william.metcalf () gmail com>
Date: Wed, 7 Apr 2010 10:09:34 -0500
Hmmm I think it can affect anything having to do with rate based alerting i.e. portscan detection or thresholding based on tracking src/dst ip addresses. I'm making the assumption that you are dividing up traffic using a bpf that was previously being watched by a single snort process. This is not a trivial task for something like a fully loaded /24 server farm or something. Another thing to note is that while there are performance advantages to be had by ensuring locality of traffic to a core, you have to make sure that you are smarter than the scheduler i.e. make sure you don't end up in a situation where a process pinned to a CPU that is pegged at 100% and four cores sitting at 10% utilization or something. ***Sham-less Plug Alert*** In suricata we have multiple ways of dividing up traffic an pining across cores. We can do this in userland based on flow, or we can even take advantage of the PF_RING clusters to divide up traffic in a flow-based or round-robin mode. While flow-pinning helps alleviate some of the guess work of traffic distribution, depending on your network you can still pretty easily end up in a situation where you have uneven distribution of traffic across your snort procs or in our case threads. With that being said, regardless of how you cut your traffic you should probably ensure that init and it's children have proper affinity set and stays away from the cores you want to dedicate to IDS otherwise the scheduler might decide that one of your IDS cores looks pretty sweet for process migration. Regards, Will 2010/4/6 Edward Bjarte Fjellskål <edward.fjellskal () redpill-linpro com>:
Jason Wallace wrote:OK so there is no affect on tracking frags, state, or anything else that might adversely affect detection. It is just a performance recommendation for folks using more than one instance of Snort?I would say its a performance recommendation for folks concerned about performance regardless of # of snort instances :) It does not affect detection other than it might help on lowering your packet-loss rate (if you have any). Snort should stick to one CPU preferably for optimal performance. That said, there are other ways to tweak snort that should be done first. Also, if you dont have any performance issues, you dont have to tune anything :) Ref: http://www.gamelinux.org/?p=81Thx, Wally------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
Current thread:
- Pin snort single processor Jason Wallace (Apr 06)
- Re: Pin snort single processor JJ Cummings (Apr 06)
- Re: Pin snort single processor Jason Wallace (Apr 06)
- Re: Pin snort single processor Edward Bjarte Fjellskål (Apr 06)
- Re: Pin snort single processor Will Metcalf (Apr 07)
- Re: Pin snort single processor Jason Wallace (Apr 06)
- Re: Pin snort single processor JJ Cummings (Apr 06)