From: Eric Dumazet <eric.dumazet@gmail.com>
To: Tom Herbert <therbert@google.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: Re: [PATCH 1/2] net: Add function to get SW rxhash
Date: Tue, 24 Sep 2013 10:03:00 -0700 [thread overview]
Message-ID: <1380042180.3165.102.camel@edumazet-glaptop> (raw)
In-Reply-To: <alpine.DEB.2.02.1309240915001.24581@tomh.mtv.corp.google.com>
On Tue, 2013-09-24 at 09:20 -0700, Tom Herbert wrote:
> Some uses of skb_get_rxhash expect that the function will return
> a consistent value whether it is called on RX or TX paths. On RX
> path, we will use the rxhash if provided by the NIC, so this
> would not normally be the same result computed in TX path which is
> a software calculation.
>
> This patch adds skb_get_sw_rxhash to explicitly request a hash
> calculated by the stack, disregarding the hash provided by NIC.
>
> Signed-off-by: Tom Herbert <therbert@google.com>
> ---
1) Adding another skb field for this corner case, is it worth it ?
Computing rxhash in software should be real fast for the
cases where we really care of symmetry.
ie ignore skb->rxhash and use __skb_get_rxhash()
2) Not copying sw_rxhash in __copy_skb_header()
-> value will be undefined after a clone()
prev parent reply other threads:[~2013-09-24 17:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-24 16:20 [PATCH 1/2] net: Add function to get SW rxhash Tom Herbert
2013-09-24 17:03 ` Eric Dumazet [this message]
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