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From: Du Fan <fengyuleidian0615@gmail.com>
To: Florian Westphal <fw@strlen.de>
Cc: Thomas Graf <tgraf@suug.ch>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jesse Gross <jesse@nicira.com>, Flavio Leitner <fbl@redhat.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	pshelar@nicira.com, netdev <netdev@vger.kernel.org>,
	"dev@openvswitch.org" <dev@openvswitch.org>,
	"Du, Fan" <fan.du@intel.com>
Subject: [Discussion] About over-MTU-sized skb in virtualized env
Date: Wed, 03 Dec 2014 14:39:37 +0800	[thread overview]
Message-ID: <547EB029.5010102@gmail.com> (raw)

Sorry for resend this mail, because my company email is rejected by netdev.


Hi Florian

  214 static int ip_finish_output_gso(struct sk_buff *skb)
  215 {
  216     netdev_features_t features;
  217     struct sk_buff *segs;
  218     int ret = 0;
  219
  220     /* common case: locally created skb or seglen is <= mtu */
  221     if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) ||
  222           skb_gso_network_seglen(skb) <= ip_skb_dst_mtu(skb))
  223         return ip_finish_output2(skb);

Could you please state _concrete_ reason why locally created skb
length is _always_ fitting into MTU size? or why we needs this
checking.
Especially in below scenario:
http://docs.openstack.org/admin-guide-cloud/content/figures/14/a/a/common/figures/under-the-hood-scenario-1-ovs-compute.png

As many people have discuss it in this thread:
http://marc.info/?t=141715669700004&r=1&w=2

             reply	other threads:[~2014-12-03  6:42 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-03  6:39 Du Fan [this message]
2014-12-03 10:50 ` [Discussion] About over-MTU-sized skb in virtualized env Florian Westphal
  -- strict thread matches above, loose matches on Subject: below --
2014-12-03  5:40 Du, Fan

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