David Miller a écrit :

From: Andi Kleen <redacted>
Date: Thu, 28 Aug 2008 00:34:10 +0200

quoted

It fixes an old performance problem at least. I'm not aware 
of any new ones in this area because the code in this 
function hasn't changed since I last looked.

That's exactly what this thread is about, things got slower for
some reason even though nothing specifically changed in this area.

I wonder if indirectly something changed in how the hash table
allocator code down in mm/*.c works, perhaps it's taking NUMA
into account differently now?

Not really, I suspect commit (a7ab4b501f9b8a9dc4d5cee542db67b6ccd1088b 
[TCPv4]: Improve BH latency in /proc/net/tcp) is responsible for longer delays.
Note that its rather old :
Date:   Sun Jun 10 17:33:08 2007 -0700


We used to disable bh once, while reading the table. This sucked.

In case machine is handling trafic, we now are preemptable by softirqs
while reading /proc/net/tcp. Thats a good thing.

By the way, I find Andi patch usefull. Same thing could be done for /proc/net/rt_cache.