[v3.2.24] ct: endless loop when initializing netfilter/ct cache

[Thomas Graf]

On 10/28/14 at 04:35pm, Holger Eitzenberger wrote:
> Sorry, I have been interrupted, now going back to this problem.
> 
> > > Turns out to be more of like a performance regresssion, as same
> > > program built against libnl v3.2.13 is considerably faster - even on a
> > > box with more conntracks...
> 
> FYI, I see the problem since changing pickup_cb() to check for
> duplicates when updating the cache.
> 
> The cache->c_items are a list of cache entries, and they are searched
> in order for a matching entry in nl_cache_search().
> 
> For a mass entity like conntracks this turns out to be very bad on
> performance.

That makes sense. Insertion through pickup became exponetionally
more expensive.

The right thing to do here is to introduce a flag to disable the
dup check for individual caches and even cache types such as CT
which do not require the dup check at all.