From: Rusty Russell <rusty@rustcorp.com.au>
To: David Miller <davem@davemloft.net>
Cc: virtualization@lists.linux-foundation.org,
herbert@gondor.apana.org.au, virtualization@lists.osdl.org,
netdev@vger.kernel.org
Subject: Re: [6/6] [VIRTIO] net: Allow receiving SG packets
Date: Tue, 22 Apr 2008 12:50:27 +1000 [thread overview]
Message-ID: <200804221250.27909.rusty@rustcorp.com.au> (raw)
In-Reply-To: <20080421.130418.01258045.davem@davemloft.net>
On Tuesday 22 April 2008 06:04:18 David Miller wrote:
> From: Rusty Russell <rusty@rustcorp.com.au>
> Date: Tue, 22 Apr 2008 05:06:16 +1000
>
> > I'm not sure what the right number is here. Say worst case is header
> > which goes over a page boundary then MAX_SKB_FRAGS in the skb, but for
> > some reason that already has a +2:
> >
> > /* To allow 64K frame to be packed as single skb without frag_list */
> > #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
> >
> > Unless someone explains, I'll change the xmit sg to 2+MAX_SKB_FRAGS as
> > well.
>
> MAX_SKB_FRAGS + 1 is what you ought to need.
Right, and so that's +2 for virtio_net because we have an extra header as
Herbert points out.
But I was curious as to why the +2 in the MAX_SKB_FRAGS definition?
Thanks,
Rusty.
next prev parent reply other threads:[~2008-04-22 2:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20080418031257.GA17993@gondor.apana.org.au>
[not found] ` <20080418032142.GD18071@gondor.apana.org.au>
[not found] ` <20080418032427.GE18071@gondor.apana.org.au>
2008-04-21 19:06 ` [6/6] [VIRTIO] net: Allow receiving SG packets Rusty Russell
2008-04-21 20:04 ` David Miller
2008-04-22 1:13 ` Herbert Xu
2008-04-22 2:50 ` Rusty Russell [this message]
2008-04-22 2:55 ` David Miller
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