From: Shaohua Li <shli@kernel•org>
To: Stephen Hemminger <stephen@networkplumber•org>
Cc: netdev@vger•kernel.org, davem@davemloft•net, Kernel-team@fb•com,
Shaohua Li <shli@fb•com>, Wei Wang <weiwan@google•com>
Subject: Re: [RFC net-next] net ipv6: convert fib6_table rwlock to a percpu lock
Date: Mon, 31 Jul 2017 19:57:04 -0700 [thread overview]
Message-ID: <20170801025704.fuhxll23d3eenwrz@kernel.org> (raw)
In-Reply-To: <20170731161007.61c2d958@xeon-e3>
On Mon, Jul 31, 2017 at 04:10:07PM -0700, Stephen Hemminger wrote:
> On Mon, 31 Jul 2017 10:18:57 -0700
> Shaohua Li <shli@kernel•org> wrote:
>
> > From: Shaohua Li <shli@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 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 <weiwan@google•com>
>
> You just reinvented brlock...
you mean lglock? It has been removed from kernel.
> RCU is not that hard, why not do it right?
Maybe. But don't think it's the reason why we shouldn't do the percpu lock now,
this is a simple change, if some smart guys find a way of RCU, we can easily
remove this.
next prev parent reply other threads:[~2017-08-01 2:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-31 17:18 [RFC net-next] net ipv6: convert fib6_table rwlock to a percpu lock Shaohua Li
2017-07-31 18:30 ` Eric Dumazet
2017-07-31 19:34 ` Shaohua Li
2017-07-31 21:20 ` [net ipv6] ee57005022: WARNING:at_kernel/softirq.c:#__local_bh_enable_ip kernel test robot
2017-07-31 23:10 ` [RFC net-next] net ipv6: convert fib6_table rwlock to a percpu lock Stephen Hemminger
2017-08-01 2:57 ` Shaohua Li [this message]
2017-08-01 7:15 ` Eric Dumazet
2017-08-01 14:45 ` Stephen Hemminger
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