netdev - Re: [PATCH RFC net-next] pktgen: introduce 'rx' mode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

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?
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html