From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alexei Starovoitov <ast@plumgrid.com>
Subject: Re: [PATCH v2 net-next] mlx4: optimize xmit path
Date: Mon, 29 Sep 2014 10:46:00 -0700
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Cc: Or Gerlitz <gerlitz.or@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	Eric Dumazet <edumazet@google.com>,
	John Fastabend <john.r.fastabend@intel.com>,
	Linux Netdev List <netdev@vger.kernel.org>,
	Amir Vadai <amirv@mellanox.com>,
	Or Gerlitz <or.gerlitz@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
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On Sun, Sep 28, 2014 at 9:19 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>         send_doorbell = !skb->xmit_more || netif_xmit_stopped(ring->tx_queue);
>
>         if (ring->bf_enabled && desc_size <= MAX_BF && !bounce &&
>             !vlan_tx_tag_present(skb) && send_doorbell) {

This patch is good,

but I've been thinking more about bf+xmit_more and want
to double check my understanding in that scenario:
xmit_more=true will queue descriptors normally and
the last xmit_more=false packet will write into BF.
I guess BF suppose to pick up the earlier ones from
the queue, otherwise the whole thing is broken.
So if indeed BF can pick up the whole chain, then
it should be the faster way than doing iowrite32(), right?