Comments on: Linux Configure Jumbo Frames to Boost Network Performance / Throughput

By: virgoptrex

virgoptrex — Fri, 15 Jan 2010 21:24:26 +0000

Can’t set mtu > 1500 on Ubuntu 9.10. This sucks! I am trying to find tweaks to fool OS but no luck yet. It works in windows very well > 9000kb jumbo size frames!

sudo ethtool eth0
gives

Settings for eth0:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Advertised auto-negotiation: Yes
Speed: 1000Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: g
Wake-on: g
Current message level: 0×000000ff (255)
Link detected: no

By: Jay A

Jay A — Thu, 25 Jun 2009 10:32:19 +0000

Hi Vivek,

What is the downside for setting higher MTU?
How would I know the proper value for MTU for my server?
I am using rhel 4 AS (2.6.9-42) , BroadCom Corporation NetXtreme II BCM5708 Gigabit Ethernet network Card and switch is 3Com® Baseline Switch 2948-SFP Plus.

Jay

By: Chris

Chris — Wed, 16 Jul 2008 13:21:39 +0000

Jeff,

Thanks for your reply. It’s strange how you have a gigabit card, yet your limit was only 100Mb/s. Perhaps you had another one, eth1? I know mine correctly has a max limit of 1000Mb/s, but somehow I couldn’t get it to work initially. I found out my card (Netgear GA311) had a max MTU of 7500, but setting that didn’t work. When I did a little bit more googling, I found out that someone who had the same card set the MTU to 7200. Once I did that, it worked for me. So I guess your initial theory was right in that the number was out of range of the max MTU.

By: jeffc

jeffc — Wed, 16 Jul 2008 01:23:18 +0000

Follow-on to my last but just got new information. Chris, open a term and do a ’sudo ethtool eth0′ or whatever your actual device is. Amongst other useful information there was this (and yes I do have a gigabit ethernet card):
Settings for eth0:
Supported ports: [ MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Advertised auto-negotiation: Yes
Speed: 100Mb/s

Sorry if that came out dodgy but the thing to note is my driver only thinks I can do 100M and as such, I would assume it would be hard for the above command to work. Well, there is a new kernel out too so I might as well grab the drivers and make a party of it…

By: jeffc

jeffc — Wed, 16 Jul 2008 01:13:09 +0000

Chris; I just had the same thing happen on Hardy and a quick Google shows that we are not alone. It must be outside the range that our drivers/hw allow for this chipset, just taking a huge swag. I really need this to work too. FWIW:
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 104
model name : AMD Turion(tm) 64 X2 Mobile Technology TL-60
nVidia MCP67 Ethernet
Linux jeff-laptop 2.6.24-19-generic #1 SMP Wed Jun 18 14:43:41 UTC 2008 i686 GNU/Linux

Will get to the bottom of this since I just spent the previous weekend rewiring the house with cat6, upgraded all routers, etc….

Jeff

By: chris

chris — Fri, 11 Jul 2008 12:52:26 +0000

Thanks for the article. I have a second ethernet card that’s a gigabit card and I tried running ifconfig eth1 mtu 9000 and it gives me an error “SIOCSIFMTU: Invalid argument”. Any idea why this is happening? Also, modifying /etc/network/interfaces didn’t seem to help either.

By: patrick

patrick — Sun, 29 Jun 2008 19:06:12 +0000

Hi, nice article
just one (1) error; for debian/ubuntu in /etc/network/interfaces, it’s mtu 9000 (mtu(space)9000) *NOT* mtu=9000 (this is only for redhat linuxes)!