From: Eric Dumazet <eric.dumazet@gmail.com>
To: Stephen Hemminger <shemminger@vyatta.com>
Cc: Tom Herbert <therbert@google.com>, netdev@vger.kernel.org
Subject: Re: Receive steering and hash and cache misses
Date: Fri, 02 Apr 2010 21:36:31 +0200 [thread overview]
Message-ID: <1270236991.1978.17.camel@edumazet-laptop> (raw)
In-Reply-To: <20100402115439.348575c9@nehalam>
Le vendredi 02 avril 2010 à 11:54 -0700, Stephen Hemminger a écrit :
> On Fri, 2 Apr 2010 10:59:43 -0700
> Tom Herbert <therbert@google.com> wrote:
>
> > On Fri, Apr 2, 2010 at 10:26 AM, Stephen Hemminger
> > <shemminger@vyatta.com> wrote:
> > >
> > > Although Receive Packet Steering can use a hardware generated receive hash
> > > the device driver still causes an unnecessary cache miss on the interrupt
> > > processing CPU. The current Ethernet network device driver receive processing
> > > has the device driver calling eth_type_trans() which causes a the
> > > interrupt CPU to read the received frame header.
> > >
> >
> > It should be possible to deduce the values set by eth_type_trans from
> > the RX descriptor along with the RX hash. I'll post the patch getting
> > rxhash from bnx2x which does this.
> >
>
> On sky2, I get only RSS, Checksum, and length from descriptor info.
Doesnt sky2 also provide vlan id (OP_RXVLAN/OP_RXCHKSVLAN) ?
A future version of hardware could provide more info perhaps...
Must eth_type_trans() be done *before* netif_receive_skb() ?
If a device provides a rxhash, maybe we can delay eth_type_trans() too.
If not, we need to access IP header anyway in the first cpu.
next prev parent reply other threads:[~2010-04-02 19:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-02 17:26 Receive steering and hash and cache misses Stephen Hemminger
2010-04-02 17:59 ` Tom Herbert
2010-04-02 18:54 ` Stephen Hemminger
2010-04-02 19:36 ` Eric Dumazet [this message]
2010-04-02 22:52 ` Stephen Hemminger
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