[nsd-users] Consequences of disable-radix-tree

David Gwynne david at gwynne.id.au
Thu Aug 25 09:41:38 CEST 2016


> On 25 Aug 2016, at 17:31, W.C.A. Wijngaards <wouter at nlnetlabs.nl> wrote:
> 
> Hi Anand,
> 
> On 25/08/16 09:11, Anand Buddhdev wrote:
>> Hi Wouter,
>> 
>> I just noticed that in the next release of NSD, there will be a
>> build-time option called "disable-radix-tree". The accompanying comment
>> says that it uses a red-black tree instead, and lowers memory usage.
>> However, this isn't a default option, so my assumption is that this has
>> other negative side effects, but there's no mention of such effects.
>> 
>> Could you please tell us more about this? Are lookups in red-black trees
>> slower? Do they use more CPU? Is there any other reason why you don't
>> use a red-black tree by default?
> 
> A small speed difference.  It is a memory-for-speed tradeoff, and the
> benefits are about 10% either way.  If memory is an obstacle; 10% speed
> hopefully isn't.  Otherwise, upgrade the machine, I guess...

are you using red black trees to do lookups of ip addresses?


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