Hi Mike and thanks for the update. According to our performance product we do NOT need an additional IFL at this time but it was included as part of the z10 upgrade so I wanted to utilize it.
Thanks, Nick -----Original Message----- From: The IBM z/VM Operating System [mailto:[email protected]] On Behalf Of Mike Walter Sent: Tuesday, January 05, 2010 9:49 AM To: [email protected] Subject: Re: 2 to 3 IFLs Nick, Disclaimer: I'm not a performance geek. I presume that you believe that you need to add a third virtual processor to each Linux guest's virtual machine definition (directory entry) for it to use the added third real processor. That's not true. Unless constrained in some way, CP will automatically spread the work of all Linux guests across all the real engines to which it has access. Adding more virtual engines to guests can actually cause more thrashing and overhead unless a performance management product clearly shows that the multithreading supported by that guest real has a bottleneck of backlogged threads tat could be dispatched on other engines. We have three z/OS running happily with two virtual general purpose engines, while CP spreads their work evenly across three real general purpose engines. Which performance product results have you been using to determine if the Linux guests need an added virtual processor? And now I turn this thread over to the real performance geeks who will happily point out any errors in my advice (which may just end up serving to inspire debate and shared knowledge). Mike Walter Hewitt Associates The opinions expressed herein are mine alone, not my employer's. "Harris, Nick J." <[email protected]> Sent by: "The IBM z/VM Operating System" <[email protected]> 01/05/2010 09:32 AM Please respond to "The IBM z/VM Operating System" <[email protected]> To [email protected] cc Subject 2 to 3 IFLs Hello All, We are upgrading our z9BC to a z10BC and increasing the IFLs from two to three. I am planning on modifying the Linux guest definitions to utilize the third IFL. Are there any performance issues or problems adding a third IFL? I can?t imagine this would do anything but help, I?m just checking. We are running z/VM 5.4 in support of Linux guests. TIA! Nick Harris Lead Systems Programmer, Information Systems [email protected] Texas Farm Bureau Insurance Companies P. O. Box 2689 Waco, TX. 76702-2689 Phone 254.751.2259 CONFIDENTIALITY STATEMENT: The foregoing message (including attachments) is covered by the Electronic Communication Privacy Act, 18 U.S.C. sections 2510-2521, and is CONFIDENTIAL. If you believe that it has been sent to you in error, do not read it. If you are not the intended recipient, you are hereby notified that any retention, dissemination, distribution, or copying of this communication is strictly prohibited. Please reply to the sender that you have received the message in error, then delete it. Thank you. . The information contained in this e-mail and any accompanying documents may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient of this message, or if this message has been addressed to you in error, please immediately alert the sender by reply e-mail and then delete this message, including any attachments. Any dissemination, distribution or other use of the contents of this message by anyone other than the intended recipient is strictly prohibited. All messages sent to and from this e-mail address may be monitored as permitted by applicable law and regulations to ensure compliance with our internal policies and to protect our business. E-mails are not secure and cannot be guaranteed to be error free as they can be intercepted, amended, lost or destroyed, or contain viruses. You are deemed to have accepted these risks if you communicate with us by e-mail.
