From: Ben Greear <greearb@candelatech.com>
To: Stephen Hemminger <shemminger@vyatta.com>
Cc: NetDev <netdev@vger.kernel.org>
Subject: Re: Why is LRO off by default on ixgbe?
Date: Wed, 23 Sep 2009 10:16:01 -0700 [thread overview]
Message-ID: <4ABA57D1.5000905@candelatech.com> (raw)
In-Reply-To: <20090923100718.79877040@s6510>
On 09/23/2009 10:07 AM, Stephen Hemminger wrote:
> 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)
Ok. It seems GRO was enabled the whole time, but LRO is what gave me the
extra performance boost.
In this particular case, I'm not actually routing, though I do have ip-forward
enabled, so I guess LRO will be OK as long as I'm careful...
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
next prev parent reply other threads:[~2009-09-23 17:15 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
2009-09-23 17:16 ` Ben Greear [this message]
2009-09-25 21:37 ` Herbert Xu
2009-09-25 21:43 ` Herbert Xu
2009-09-25 21:53 ` Ben Greear
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4ABA57D1.5000905@candelatech.com \
--to=greearb@candelatech.com \
--cc=netdev@vger.kernel.org \
--cc=shemminger@vyatta.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).