From: David Vrabel <david.vrabel@citrix•com>
To: Wei Liu <wei.liu2@citrix•com>
Cc: Paul Durrant <Paul.Durrant@citrix•com>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
Ian Campbell <Ian.Campbell@citrix•com>,
David Vrabel <david.vrabel@citrix•com>,
"xen-devel@lists•xen.org" <xen-devel@lists•xen.org>
Subject: Re: [Xen-devel] [PATCH net-next v4 2/5] xen-netback: add support for IPv6 checksum offload from guest
Date: Mon, 14 Oct 2013 13:19:20 +0100 [thread overview]
Message-ID: <525BE148.1010508@citrix.com> (raw)
In-Reply-To: <20131014105527.GD11739@zion.uk.xensource.com>
On 14/10/13 11:55, Wei Liu wrote:
> On Mon, Oct 14, 2013 at 11:49:20AM +0100, Paul Durrant wrote:
>>> -----Original Message-----
>>> From: Wei Liu [mailto:wei.liu2@citrix•com]
>>> Sent: 14 October 2013 11:43
>>> To: Paul Durrant
>>> Cc: xen-devel@lists•xen.org; netdev@vger•kernel.org; Wei Liu; David Vrabel;
>>> Ian Campbell
>>> Subject: Re: [PATCH net-next v4 2/5] xen-netback: add support for IPv6
>>> checksum offload from guest
>>>
>>> On Fri, Oct 11, 2013 at 04:06:19PM +0100, Paul Durrant wrote:
>>> [...]
>>>> -/*
>>>> - * This is the amount of packet we copy rather than map, so that the
>>>> - * guest can't fiddle with the contents of the headers while we do
>>>> - * packet processing on them (netfilter, routing, etc).
>>>> +/* This is a miniumum size for the linear area to avoid lots of
>>>> + * calls to __pskb_pull_tail() as we set up checksum offsets.
>>>> */
>>>
>>> You seem to forget to explain why 128 is chosen. :-)
>>
>> Is that not sufficient explanation? What sort of thing are you looking for?
>>
>
>>From the second version of this patch, we had a conversation.
>
>> Where does 128 come from?
>>
>
> "It's just an arbitrary power of 2 that was chosen because it seems to
> cover most likely v6 headers and all v4 headers."
>
> So something like: "We choose 128 which is likely to cover most V6
> headers and all V4 headers" would be sufficeint.
Is "most IPv6 headers" actually good enough? Don't we need to ensure
netback copies all IP headers?
David
next prev parent reply other threads:[~2013-10-14 12:19 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-11 15:06 [PATCH net-next v4 0/5] xen-netback: IPv6 offload support Paul Durrant
2013-10-11 15:06 ` [PATCH net-next v4 1/5] xen-netback: add support for IPv6 checksum offload to guest Paul Durrant
2013-10-14 10:53 ` Ian Campbell
2013-10-14 11:10 ` Paul Durrant
2013-10-16 16:10 ` Ian Campbell
2013-10-11 15:06 ` [PATCH net-next v4 2/5] xen-netback: add support for IPv6 checksum offload from guest Paul Durrant
2013-10-14 10:42 ` Wei Liu
2013-10-14 10:49 ` Paul Durrant
2013-10-14 10:55 ` Wei Liu
2013-10-14 10:57 ` Paul Durrant
2013-10-14 12:19 ` David Vrabel [this message]
2013-10-14 12:34 ` [Xen-devel] " Paul Durrant
2013-10-16 16:11 ` Ian Campbell
2013-10-16 16:57 ` Paul Durrant
2013-10-11 15:06 ` [PATCH net-next v4 3/5] xen-netback: Unconditionally set NETIF_F_RXCSUM Paul Durrant
2013-10-14 10:56 ` Ian Campbell
2013-10-14 11:03 ` Paul Durrant
2013-10-11 15:06 ` [PATCH net-next v4 4/5] xen-netback: handle IPv6 TCP GSO packets from the guest Paul Durrant
2013-10-16 16:15 ` Ian Campbell
2013-10-16 16:16 ` Ian Campbell
2013-10-11 15:06 ` [PATCH net-next v4 5/5] xen-netback: enable IPv6 TCP GSO to " Paul Durrant
2013-10-16 16:49 ` Ian Campbell
2013-10-16 16:52 ` Paul Durrant
2013-10-16 17:01 ` Ian Campbell
2013-10-16 16:20 ` [Xen-devel] [PATCH net-next v4 0/5] xen-netback: IPv6 offload support Ian Campbell
2013-10-16 16:53 ` Paul Durrant
2013-10-16 17:00 ` Ian Campbell
2013-10-17 8:42 ` Paul Durrant
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