From: John Fastabend <john.fastabend@gmail.com>
To: Alexei Starovoitov <ast@plumgrid.com>,
David Miller <davem@davemloft.net>
Cc: daniel@iogearbox.net, jhs@mojatatu.com, jiri@resnulli.us,
netdev@vger.kernel.org
Subject: Re: [PATCH net-next] tc: fix tc actions in case of shared skb
Date: Tue, 14 Jul 2015 17:58:15 -0700 [thread overview]
Message-ID: <55A5B027.70604@gmail.com> (raw)
In-Reply-To: <55A59657.2050100@plumgrid.com>
On 15-07-14 04:08 PM, Alexei Starovoitov wrote:
> On 7/14/15 3:34 PM, David Miller wrote:
>>>>> 1 get rid of burst hack for both RX and TX in pktgen (kills
>>>>> >>>performance)
>> #1 is a serious consideration if you don't come up with better ideas,
>> since an optimization is for nothing if it knowingly breaks things.
>
> I've dug up the pktgen source from 2002 and see:
> atomic_inc(&skb->users);
> odev->hard_start_xmit(skb, odev);
> so it did this trick forever.
> Looks like it's a fundamental way how pktgen was working
> and working still. Even when new 'burst' feature is not used,
> pktgen still increments skb->users to hold skb.
> At present I don't have good ideas how to redesign pktgen
> and since apparently no one noticed this tc_action+pktgen
> breakage for years, it's probably ok to leave everything as-is until
> better ideas come. I'm not giving up yet. Just ran out of ideas.
>
Right and we hit this issue when pktgen is run over any stacked device
with clone_skb set. I've always put it in the don't do this category but
a fix would be nice.
> --
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next prev parent reply other threads:[~2015-07-15 0:58 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-11 0:10 [PATCH net-next] tc: fix tc actions in case of shared skb Alexei Starovoitov
2015-07-12 4:29 ` David Miller
2015-07-13 19:47 ` Alexei Starovoitov
2015-07-13 20:04 ` David Miller
2015-07-13 20:17 ` Alexei Starovoitov
2015-07-13 20:55 ` Daniel Borkmann
2015-07-13 22:26 ` Alexei Starovoitov
2015-07-14 10:29 ` Daniel Borkmann
2015-07-14 11:57 ` Jamal Hadi Salim
2015-07-14 12:19 ` Daniel Borkmann
2015-07-14 15:46 ` Alexei Starovoitov
2015-07-14 22:34 ` David Miller
2015-07-14 23:08 ` Alexei Starovoitov
2015-07-15 0:58 ` John Fastabend [this message]
2015-07-15 1:01 ` Alexei Starovoitov
2015-07-13 13:13 ` Jamal Hadi Salim
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