On 8/4/17 11:07 AM, Eric Dumazet wrote: > On Fri, 2017-08-04 at 09:38 -0700, Shaohua Li wrote: >> From: Shaohua Li <s...@fb.com> >> >> 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 (lglock has >> been removed from kernel, so I added a simple implementation here) 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. >> >> Of course the percpu lock isn't as good as rcu, so this isn't intended >> to replace rcu, but this is much better than current readwrite lock. >> Before we have a rcu implementation, this is a good temporary solution. >> Plus, this is a trival change, there is nothing to prevent pursuing a >> rcu implmentation. >> >> Cc: Wei Wang <wei...@google.com> >> Cc: Eric Dumazet <eric.duma...@gmail.com> >> Cc: Stephen Hemminger <step...@networkplumber.org> >> Signed-off-by: Shaohua Li <s...@fb.com> >> --- > > Wei has almost done the RCU conversion. > > This patch is probably coming too late.
+1 I'd rather see the RCU conversion than a move to per-cpu locks.
