[Oisf-users] Suricata, 10k rules, 10Gbit/sec and lots of RAM

Gary Faulkner gfaulkner.nsm at gmail.com
Thu Dec 10 02:06:54 UTC 2015

What kind of memory settings are folks using with this branch within the
config file and what was the end result in terms of total memory usage
compared to number of workers configured?

On 12/9/2015 2:11 PM, Cooper F. Nelson wrote:
> On 12/9/2015 5:36 AM, Victor Julien wrote:
> > Our main performance hit in the multi pattern matching (mpm) stage.
> > We've used a skip based algorithm in the past (b2g is still in our
> > tree), but performance with AC is quite a lot better. Generally the
> > problem for IDS patterns is that they are of poor quality, many 1 and
> > 2 byte patterns. These defeat the skip based algo's. Another issue
> > that is important to us is the worst-case performance. The skip based
> > algo's seem to have a worse worst case profile.
> As I was walking to the pub last night I remembered that suricata has
> migrated to AC some time ago!  Thanks for the details regardless, it's
> very interesting.
> > Btw, I recently saw a new paper on a mix of AC and skip based approach
> > that I still have to take a deeper look at:
> > http://halcyon.usc.edu/~pk/prasannawebsite/papers/HeadBody_camera.pdf
> - From the paper:
> > In [14], a throughput of 7.5 Gbps was achieved
> > using 32 processors in a Cray XMT supercomputer. There
> > is yet a cost-efficient DBSM solution capable of matching
> > 10 Gbps traffic against several thousand strings on a multicore
> > platform.
> I've been doing this for years with suricata and a small bpf filter, on
> a 16 core (actually 8 w/hyper-threading) Xeon server.  Over 20k
> signatures, too.  I will admit the EmergingThreats guys do a fabulous
> job of optimizing their signatures for efficiency.
> As I mentioned previously the actual suricata process is only processing
> a fraction of the original packets, but if you are primarily interested
> in matching against HTTP headers I don't particularly see the value of a
> full DPI solution.  Particularly when you allow services like Netflix
> and Youtube on your network.
> The real bottleneck on all modern multi-core Von-Neumann style
> architectures is memory (particularly cache memory) I/O.  So this is
> less of problem with the performance of the pattern-matching engine as
> it's an issue with memory pressure put on the various core sub-systems
> by attempting to match against full TCP flows.  The authors allude to
> this at points, however I think if they ran better performance counters
> this would be more obvious.
> The tl;dr is that what they are discussing *is* possible if you
> pre-process your IP traffic via an efficient byte-based pattern matcher
> like bpf.  This is why packet filters were invented, in fact.
> I guess its possible that they are already working with sampled traffic,
> but I doubt it.
> > Finally, we should start experimenting with Intel's Hyperscan soon.
> > They claim much better perf, so we will see :)
> Ok now this is interesting and a new thing for me.  My next question for
> you was if you were still looking at using SSE for pattern-matching.
> Especially in the context of Aho-Corasick, as I would think it would be
> possible to analyze multiple flows/packets/patterns in parallel via a
> SIMD approach.  Great to see this is open-source, too.
> There is a concern that SSE breaks hyperthreading to an extent, in that
> hyper-threaded cores share a single FP/SSE execution pipeline.  However,
> I would think the performance benefits afforded by vectorizing the
> regexp process would exceed any losses incurred by losing 1-2
> traditional integer pipelines.
> Anyways, this if fabulously exciting and would be willing and able to
> help test this once available.
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