Hi, We found this: http://www-03.ibm.com/systems/z/os/linux/pdf/avmlinux.pdf
VM Scheduler Resource Settings Linux is a long-running virtual machine, and VM by default is setup for short-running guests, so the following change to the VM scheduler settings should be made. We recommend setting storbuf=300,200,200 and ldubuf=100,100,100. Linux is a Q3 virtual machine, so changing this third setting is most important. Include these settings in the profile exec for the operator machine or autolog1 machine: “set srm storbuf=300,200,200” and “set srm ldubuf=100,100,100”. We bumped LDUBUF up. q srm IABIAS : INTENSITY=90%; DURATION=2 LDUBUF : Q1=100% Q2=100% Q3=100% STORBUF: Q1=300% Q2=200% Q3=200% DSPBUF : Q1=32767 Q2=32767 Q3=32767 DISPATCHING MINOR TIMESLICE = 5 MS MAXWSS : LIMIT=9999% ...... : PAGES=999999 XSTORE : 0% Thank you, Dave H. Barton Robinson <[EMAIL PROTECTED]> Sent by: The IBM z/VM Operating System <IBMVM@LISTSERV.UARK.EDU> 03/21/2008 01:33 PM Please respond to The IBM z/VM Operating System <IBMVM@LISTSERV.UARK.EDU> To IBMVM@LISTSERV.UARK.EDU cc Subject Re: Performance problem Linux under Zvm The guideline for LDUBUF is to LOWER it from default, NEVER raise it unless you like to re-IPL z/VM. O'Brien, David W. (NIH/CIT) [C] wrote: > I made the mistake of believing what I was told. > > cp q storage > 05:57:21 STORAGE = 2G > Ready; T=0.01/0.01 05:57:21 > cp q virtual storage > 05:57:35 STORAGE = 128M > Ready; T=0.01/0.01 05:57:35 > > cp q srm > 06:01:42 IABIAS : INTENSITY=90%; DURATION=2 > 06:01:42 LDUBUF : Q1=100% Q2=75% Q3=60% > 06:01:42 STORBUF: Q1=300% Q2=300% Q3=300% > 06:01:42 DSPBUF : Q1=32767 Q2=32767 Q3=32767 > 06:01:42 DISPATCHING MINOR TIMESLICE = 5 MS > 06:01:42 MAXWSS : LIMIT=9999% > 06:01:42 ...... : PAGES=999999 > 06:01:42 XSTORE : 0% > > Any recommendation for LDUBUF? I just raised it to 100 100 100. Please advise if that change was counter indicated. > > Thank you, > Dave O'Brien > National Institutes of Health > > > ________________________________ > > From: Gentry, Stephen [Sent: Thu 3/20/2008 2:51 PM > Subject: Re: Performance problem Linux under Zvm > > > > What command did you use to determine that you had 768m central storage? > QUERY STOREAGE? > QUERY VIRTUAL STORAGE? > Steve G. > > -----Original Message----- > Subject: Re: Performance problem Linux under Zvm > > Thanks John > > cp q srm > IABIAS : INTENSITY=90%; DURATION=2 > LDUBUF : Q1=100% Q2=75% Q3=60% > STORBUF: Q1=300% Q2=200% Q3=200% > DSPBUF : Q1=32767 Q2=32767 Q3=32767 > DISPATCHING MINOR TIMESLICE = 5 MS > MAXWSS : LIMIT=9999% > ...... : PAGES=999999 > XSTORE : 0% > > Just got the following from one of the other techs (non-VM) > > > We were able to diagnose the problem and make the necessary correction. > > The problem was z/VM has a total 768m of central available. The Linux > guests (3 total) each had 768m of central allocated, therefore > contention. > > The Linux guests are over allocated and are storage constrained with > 768m of central. > > Understanding the Linux guests would be in contention with each other > for this storage VM time sliced what it could for each > > guest, therefore the symptoms we experienced. > > > > My question to this group - Does a Linux quest really require 768MB of > Central? > > Regards, > > Dave O'Brien > > > ________________________________ > > From: Romanowski, John (OFT) > Subject: Re: Performance problem Linux under Zvm > > > > If CP INDICATE QUEUES shows an En (like E3) > in the 2nd column for one or more userids > try CP QUERY SRM (write down response for reviewing ) > and do this quick fix > CP SET SRM STORBUF 300% 300% 300% > > > -------------------------------------------------------- > This e-mail, including any attachments, may be confidential, privileged > or otherwise legally protected. It is intended only for the addressee. > If you received this e-mail in error or from someone who was not > authorized to send it to you, do not disseminate, copy or otherwise use > this e-mail or its attachments. Please notify the sender immediately by > reply e-mail and delete the e-mail from your system. > > > -----Original Message----- > > Subject: Performance problem Linux under Zvm > > Our shop is new to Zvm and Linux. We have a very small number of Linux > users who are reporting significant response time problems. It almost > seems as if each stops running for a period of time and is then > re-dispatched. > > Is there a VM parameter that we might have taken the default on that > needs tweaking? > > Any help or advice appreciated as this is a proof of concept endeavour > and we would like not to turn off prospective users from the start. > > Thank you, > Dave O'Brien > National Institutes of Health > > Disclaimer: Information in this message or an attachment may be government data and thereby subject to the Minnesota Government Data Practices Act, Minnesota Statutes, Chapter 13, may be subject to attorney-client or work product privilege, may be confidential, privileged, proprietary, or otherwise protected, and the unauthorized review, copying, retransmission, or other use or disclosure of the information is strictly prohibited. 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