From 90f586dba1465a73295d752abe2451e924ba1888 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Timo=20Ter=C3=A4s?= Date: Mon, 27 May 2013 08:33:10 +0300 Subject: [PATCH 4/6] ipv4: rate limit updating of next hop exceptions with same pmtu MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The tunnel devices call update_pmtu for each packet sent, this causes contention on the fnhe_lock. Ignore the pmtu update if pmtu is not actually changed, and there is still plenty of time before the entry expires. Signed-off-by: Timo Teräs --- net/ipv4/route.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 8dedfeb..85b9c07 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -947,6 +947,10 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) if (mtu < ip_rt_min_pmtu) mtu = ip_rt_min_pmtu; + if (rt->rt_pmtu == mtu && + time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2)) + return; + rcu_read_lock(); if (fib_lookup(dev_net(dst->dev), fl4, &res) == 0) { struct fib_nh *nh = &FIB_RES_NH(res); -- 1.8.2.3