Subject: Re: OSA/Express - This Doesn't Make Any Sense!
From: Kevin Corkery (kcorkery@comcast.net)
Date: Mon Aug 18 2008 - 16:48:52 EDT
One comment on this solution since this also applied to my VTAPE performance issue. There is documentation on the IBM web-site that would indicate the tweaking the defaults of the TCP/IP $SOCKOPT will suffice. I found that the regestry change on the Windows server was really required to achieve the desired effect. I think that IBM and the IP stack vendors should cooperate on a document that details what needs to be done to achieve the highest performance for there varied uses of the TP connectivity to the LAN. The performance of the FTP raffic is obvious but we are seeing more applications (VSAM redirector, VTAPE, etc) that inherently benefit from very high performance since they tend to have "windowed" requirements. When you have a 1GB QDIO Ethernet adapter it's a good thing to be able to show some performance for the investment; let's not make Windows make the VSE side look bad. And yes, contrary to popular belief, Linux will not be supplanting Windows any time soon. -- Kevin Corkery Independent Consultant Voorhees, New Jersey -------------- Original message ---------------------- From: "David Stuart" <David.Stuart@ventura.org> > Afternoon All, > > Ok, it appears to be fixed. > > To recap, the actions taken were to 'hard code' the OSA/Express ports to 100 > mbps full-duplex (instead of letting it auto-negotiate), and adding the Win/XP > Registry Key value TcpAckFrequency and setting it to 1. > > Between the two, I now download as fast as I upload. A recent test hit a peak > of 4.1MBps/second. > > Thanks to all who had suggestions, and Jeff and Mike for pointing me to > TcpAckFrequency. > > > Thanks, > Dave > > > > > > > > Dave Stuart > Prin. Info. Systems Support Analyst > County of Ventura, CA > 805-662-6731 > David.Stuart@ventura.org > > >>> "David Stuart" <David.Stuart@ventura.org> 8/18/2008 9:33 AM >>> > Hi Jeff, > > I'm working on it. I found the MS article that Mike Moore pointed me to. I > have added the registry values. Next, I think I need to reboot. I should be > able to do some testing later this morning. > > > Dave > > > > Dave Stuart > Prin. Info. Systems Support Analyst > County of Ventura, CA > 805-662-6731 > David.Stuart@ventura.org > > >>> "Jeffrey Barnard" <bsiopti@bsiopti.com> 8/18/2008 9:05 AM >>> > David, > > I think you will find that adding a registry entry for TcpAckFrequency > Full_Dword = 1 will disable the Windows ACK delay and fix your problem. I > was able to re-create the issue here on a Windows XP SP3 box and this fixed > the problem. Verify you have the require hotfix applied too (if needed, SP3 > already has it applied). > > FWIW, My Linux systems do not have this problem and have higher transfer > rates too. > > Regards, > Jeff > > -- > Jeffrey C Barnard > Barnard Software, Inc. http://www.bsiopti.com > BSI 407-323-4773 Support 407-688-7123 > > > > > >
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