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Message-ID: <55416905.7070308@plumgrid.com>
Date:	Wed, 29 Apr 2015 16:28:05 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Daniel Borkmann <daniel@...earbox.net>,
	Thomas Graf <tgraf@...g.ch>,
	Jamal Hadi Salim <jhs@...atatu.com>,
	John Fastabend <john.r.fastabend@...el.com>,
	netdev@...r.kernel.org
Subject: Re: [PATCH RFC net-next] pktgen: introduce 'rx' mode

On 4/29/15 3:56 PM, Eric Dumazet wrote:
>
> So pktgen in RX mode MUST deliver skb with skb->users = 1, there is no
> way around it.

if I only knew how to do it...
The cost of continuously allocating skbs is way higher than
netif_receive_skb itself. Such benchmarking tool would measure the
speed of skb alloc/free instead of speed of netif_receive_skb.
Are you suggesting to pre-allocate 10s of millions of skbs and
then feed them in one go? The profile will be dominated by
cache misses in the first few lines of __netif_receive_skb_core()
where it accesses skb->dev,data,head. Doesn't sound too useful either.
Other thoughts?
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