From: Shirley Ma <mashirle@us.ibm.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: David Miller <davem@davemloft.net>,
Eric Dumazet <eric.dumazet@gmail.com>,
Avi Kivity <avi@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
netdev@vger.kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3 2/8] Add a new zerocopy device flag
Date: Tue, 03 May 2011 13:11:21 -0700 [thread overview]
Message-ID: <1304453481.20660.39.camel@localhost.localdomain> (raw)
In-Reply-To: <1304444570.20660.32.camel@localhost.localdomain>
On Tue, 2011-05-03 at 10:42 -0700, Shirley Ma wrote:
> Better to prevent this kind of skbs to be used in skb_clone, expand
> head
> for now.
I looked at the code, skb_clone shouldn't have any problem since ubuf
callback is only called after the lower device DMA has done. I can
modify the zerocopy len to 256 bytes so expand head should be OK as
well. So we only need to prevent recycle skb. I also checked the device
drivers, only a few device do RX buffers recycle. So there shouldn't be
any problem.
I will add more comments here to make sure when ZEROCOPY flag is set,
the ubuf callback should only be called when last reference to this skb
is gone.
Thanks
Shirley
next prev parent reply other threads:[~2011-05-03 20:11 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-20 19:36 [PATCH V3 0/8] macvtap/vhost TX zero copy support Shirley Ma
2011-04-20 19:42 ` [PATCH V3 1/8] Add a new sock zerocopy flag Shirley Ma
2011-04-20 19:44 ` [PATCH V3 2/8] Add a new zerocopy device flag Shirley Ma
2011-04-20 19:48 ` Ben Hutchings
2011-04-20 20:05 ` Shirley Ma
2011-04-20 20:09 ` Shirley Ma
2011-04-20 20:24 ` Dimitris Michailidis
2011-04-20 20:28 ` Shirley Ma
2011-04-20 20:30 ` Shirley Ma
2011-05-02 10:42 ` Michael S. Tsirkin
2011-05-02 18:47 ` Shirley Ma
2011-05-02 19:53 ` Michael S. Tsirkin
2011-05-03 17:42 ` Shirley Ma
2011-05-03 20:11 ` Shirley Ma [this message]
2011-04-20 19:47 ` [PATCH V3 3/8] Add userspace buffers support in skb Shirley Ma
2011-05-02 10:53 ` Michael S. Tsirkin
2011-05-03 17:36 ` Shirley Ma
2011-04-20 20:07 ` [PATCH V3 4/8] vhost TX zero copy support Shirley Ma
2011-04-20 20:12 ` [PATCH V3 0/8] macvtap/vhost " Shirley Ma
2011-04-20 20:13 ` [PATCH V3 5/8] Enable cxgb3 to support zerocopy Shirley Ma
2011-04-20 20:52 ` Dimitris Michailidis
2011-04-20 20:58 ` Shirley Ma
2011-04-20 21:15 ` Shirley Ma
2011-04-20 20:15 ` [PATCH V3 7/8] Enable ixgbe " Shirley Ma
2011-04-20 20:17 ` [PATCH V3 8/8] Enable benet " Shirley Ma
2011-04-20 20:27 ` [PATCH V3 6/8] macvtap/vhost TX zero copy support Shirley Ma
2011-05-02 18:35 ` Shirley Ma
2011-04-21 14:29 ` [PATCH V3 0/8] " Jon Mason
2011-04-22 17:31 ` Shirley Ma
2011-04-22 17:52 ` Shirley Ma
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