From: Qin Chuanyu <qinchuanyu@huawei.com>
To: <jasowang@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>,
"Anthony Liguori" <anthony@codemonkey.ws>,
KVM list <kvm@vger.kernel.org>, <netdev@vger.kernel.org>
Subject: 8% performance improved by change tap interact with kernel stack
Date: Tue, 28 Jan 2014 16:14:12 +0800 [thread overview]
Message-ID: <52E766D4.4070901@huawei.com> (raw)
according perf test result，I found that there are 5%-8% cpu cost on
softirq by use netif_rx_ni called in tun_get_user.
so I changed the function which cause skb transmitted more quickly.
from
tun_get_user ->
netif_rx_ni(skb);
to
tun_get_user ->
rcu_read_lock_bh();
netif_receive_skb(skb);
rcu_read_unlock_bh();
The test result is as below:
CPU: Intel(R) Xeon(R) CPU E5620 @ 2.40GHz
NIC: intel 82599
Host OS/Guest OS:suse11sp3
Qemu-1.6
netperf udp 512(VM tx)
test model: VM->host->host
modified before : 2.00Gbps 461146pps
modified after : 2.16Gbps 498782pps
8% performance gained from this change,
Is there any problem for this patch ?
next reply other threads:[~2014-01-28 8:14 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-28 8:14 Qin Chuanyu [this message]
2014-01-28 8:34 ` 8% performance improved by change tap interact with kernel stack Michael S. Tsirkin
2014-01-28 9:14 ` Qin Chuanyu
2014-01-28 9:41 ` Michael S. Tsirkin
2014-01-28 10:19 ` Qin Chuanyu
2014-01-28 10:33 ` Michael S. Tsirkin
2014-01-28 16:58 ` Stephen Hemminger
2014-01-28 17:18 ` Michael S. Tsirkin
2014-01-29 7:41 ` Qin Chuanyu
2014-01-29 7:56 ` Michael S. Tsirkin
2014-01-28 16:56 ` Rick Jones
2014-01-28 14:49 ` Eric Dumazet
2014-01-29 7:12 ` Qin Chuanyu
2014-02-11 13:21 ` Qin Chuanyu
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