topic Re: ping latency observed on HP Proliant DL385 G2 in Operating System - Linux

ping latency observed on HP Proliant DL385 G2

Peter Hawkey-Noble — Thu, 07 Aug 2008 12:38:45 GMT

Using the above hardware and using Broadcom NetXtreme II Gigabit Ethernet Driver bnx2 v1.7.1c (December 27, 2007) With RedHat el 3.0 kernel version 2.4.21-37.ELSmp processor, Dual-Core AMD Opteron(tm) Processor 2218, we are observing what appears to be a network latency internal to the server of approx 1.5 secs. This has been checked using a network sniffer. From the machine pinged to return, the packets are taking < 300 micro secs. What is causing the latency and what is the resolution to it?

Re: ping latency observed on HP Proliant DL385 G2

Steven E. Protter — Thu, 07 Aug 2008 17:36:43 GMT

Shalom,

use mii-tool or ethtool to make sure you have a full duplex connection.

If you do not, correct the OS and if needed the switch.

If you do have a full duplex connection, check the network infrastructure, I doubt there is anything with your system that can cause this save a bad NIC. I'd check that with the DL385 hardware utilities.

SEP

Re: ping latency observed on HP Proliant DL385 G2

TwoProc — Tue, 12 Aug 2008 13:24:45 GMT

Right about what Steven's getting at.

That is, I think you're mixing duplexes ( if I can call it that).

Make sure that you have both the server port, and the port at the switch set to FULL duplex.

If not, you'll see what you're experiencing, you'll have connectivity, but very slow connectivity. What can get you in trouble is the "AUTO" setting on either the server or on the switch - try to avoid it.

Re: ping latency observed on HP Proliant DL385 G2

Peter Hawkey-Noble — Tue, 12 Aug 2008 13:48:36 GMT

Hi Thanks for your replies, they are very useful:

I have attached the stack trace that we have from this nic card, i dont know whether this will tell you anything or not>

Regards

Peter

Re: ping latency observed on HP Proliant DL385 G2

TwoProc — Wed, 13 Aug 2008 14:29:26 GMT

Peter,

I don't see much in the stack trace that helps, have you looked at your settings on the switch and the server? Once again - set them both to FULL and your problem should go away.

Re: ping latency observed on HP Proliant DL385 G2

Peter Hawkey-Noble — Wed, 13 Aug 2008 15:07:36 GMT

Thanks very much for your answer, settings on the switch and the card have been set to full. Looks more like a driver and kernel problem is occurring here, I am going to try and find an intel card and driver that are compatible with the kernel.

Peter

Re: ping latency observed on HP Proliant DL385 G2

Court Campbell — Wed, 13 Aug 2008 16:14:44 GMT

You may also want to check your speed with ethtool. I had an occassion where a new server was setup and got plugged into a switch port that was statically configured for 10Mbit.

Re: ping latency observed on HP Proliant DL385 G2

Ravindra Muniraj — Tue, 07 Oct 2008 12:46:24 GMT

For more information, please refer the below links:

http://wiki.ljackson.us/Negative_Ping_Time

OR

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&taskId=110&prodSeriesId=446006&prodTypeId=15351&objectID=c01075682

AMD driver link is following:-
http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_871_13118,00.html

Re: ping latency observed on HP Proliant DL385 G2

Peter Hawkey-Noble — Tue, 07 Oct 2008 13:26:50 GMT

Hello All:

Many thanks to all the contributers, It would seem that the nic card driver and kernel version being used were not compatible. A compatible card was found and installed and set to full duplex, this has resolved the problem. The replies with reference to the CPU clocking have been particularly useful re time drift.

Once again I thank you all.

Peter