From: "Yan, Zheng" <zheng.z.yan@intel.com>
To: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"davem@davemloft.net" <davem@davemloft.net>
Cc: "Shi, Alex" <alex.shi@intel.com>
Subject: [PATCH] ipv4: Cache local output routes
Date: Mon, 13 Aug 2012 14:09:59 +0800 [thread overview]
Message-ID: <50289A37.6000209@intel.com> (raw)
Commit caacf05e5ad1abf causes big drop of UDP loop back performance.
The cause of the regression is that we do not cache the local output
routes. Each time we send a datagram from unconnected UDP socket,
the kernel allocates a dst_entry and adds it to the rt_uncached_list.
It creates lock contention on the rt_uncached_lock.
Reported-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
---
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index e4ba974..fd9ecb5 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2028,7 +2028,6 @@ struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *fl4)
}
dev_out = net->loopback_dev;
fl4->flowi4_oif = dev_out->ifindex;
- res.fi = NULL;
flags |= RTCF_LOCAL;
goto make_route;
}
next reply other threads:[~2012-08-13 6:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-13 6:09 Yan, Zheng [this message]
2012-08-14 21:47 ` [PATCH] ipv4: Cache local output routes David Miller
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