From: Stephen Hemminger <shemminger@vyatta.com>
To: Ben Greear <greearb@candelatech.com>
Cc: NetDev <netdev@vger.kernel.org>
Subject: Re: Why is LRO off by default on ixgbe?
Date: Wed, 23 Sep 2009 10:07:18 -0700 [thread overview]
Message-ID: <20090923100718.79877040@s6510> (raw)
In-Reply-To: <4ABA538F.7020507@candelatech.com>
On Wed, 23 Sep 2009 09:57:51 -0700
Ben Greear <greearb@candelatech.com> wrote:
> On 09/23/2009 09:53 AM, Stephen Hemminger wrote:
> > On Wed, 23 Sep 2009 09:29:59 -0700
> > Ben Greear<greearb@candelatech.com> wrote:
> >
> >> I just noticed that enabling LRO on ixgbe lets me reach about 9Gbps receive on two
> >> NICs concurrently in an NFS test, where I was only getting about 6Gbps w/out it (1500 MTU).
> >>
> >> Why is LRO disabled by default?
> >>
> >> Thanks,
> >> Ben
> >
> > LRO is turned off if bridging or routing because of End to End requirements.
>
> That makes sense.
>
> If I know that all interfaces in question can handle TSO and LRO,
> I could manually enable LRO w/out risk, right?
>
The problem is that LRO merges TCP packets, this breaks the end-to-end
ack clocking and checksumming, and therefore is not enabled.
That is why GRO is the replacement solution (preserves packet boundaries)
next prev parent reply other threads:[~2009-09-23 17:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-23 16:29 Why is LRO off by default on ixgbe? Ben Greear
2009-09-23 16:53 ` Stephen Hemminger
2009-09-23 16:57 ` Ben Greear
2009-09-23 17:07 ` Stephen Hemminger [this message]
2009-09-23 17:16 ` Ben Greear
2009-09-25 21:37 ` Herbert Xu
2009-09-25 21:43 ` Herbert Xu
2009-09-25 21:53 ` Ben Greear
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