On Mon, 31 Jul 2017 19:57:04 -0700
Shaohua Li [off-list ref] wrote:

On Mon, Jul 31, 2017 at 04:10:07PM -0700, Stephen Hemminger wrote:

quoted

On Mon, 31 Jul 2017 10:18:57 -0700
Shaohua Li [off-list ref] wrote:
  

quoted

From: Shaohua Li <redacted>

In a syn flooding test, the fib6_table rwlock is a significant
bottleneck. While converting the rwlock to rcu sounds straighforward,
but is very challenging if it's possible. A percpu spinlock is quite
trival for this problem since updating the routing table is a rare
event. In my test, the server receives around 1.5 Mpps in syn flooding
test without the patch in a dual sockets and 56-CPU system. With the
patch, the server receives around 3.8Mpps, and perf report doesn't show
the locking issue.

Cc: Wei Wang <redacted>  

You just reinvented brlock...

It was a long time ago (2.4) that brlock came in
 https://lwn.net/Articles/378781/

I removed it in 2.5.64 or so.