Velocity Software, Inc - XIP for Linux1 XIP (eXecute In Place) for Linux on z/VM Implementation and Analysis [email protected] HTTP://VelocitySoftware.com

Velocity Software, Inc - XIP for Linux

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XIP (eXecute In Place) for Linux on

z/VM Implementation and Analysis

[email protected]://VelocitySoftware.comHTTP://LinuxVM.com

Tony NotoVelocity Software196-D Castro StreetMountain View, CA 94041(650) 964-8867 Phone(650) 964-9012 Fax

November 2005


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Agenda

Implementation procedures for XIP Targeting processes / libraries Performance Analysis


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XIP Implementation Reference:

How to use Execute-in-Place Technology with Linux on z/VM (SC33-8283)

SHARE 2005 presentation 9266 by Dr. Holger Smolinski

VM Shared Kernel Support (http://www.vm.ibm.com/linux/linuxnss.html)

Watch this space for new RedBook

Two environments Flex system, z/VM 4.3, 512Meg, SLES9 31-bit service-pack 2 Z990 z/VM, 5.1, 20Gig, SLES9 64-bit service-pack2


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XIP Implementation SLES9 has an older but still valid XIP version built

in The current XIP is delivered in source as diffs

apparently need the kernel tree to compile it. Download the XIP shell scripts from

http://www.ibm.com/developerworks/linux/linux390/april2004_documentation.html

http://awlinux1.alphaworks.ibm.com/developerworks/linux390/src/xip-howto-scripts-v1.tgz




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XIP Implementation

Case 1 – z/VM 4.3 SLES9 31-bit Virtual machine size – 256M Moving NETSNMP to DCSS File specific Sharing


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The Process- This process follows, pretty closely, the procedure as defined in SC33-

8283 How to use Execute-in-Place Technology with Linux on z/VM- Download the XIP scripts into the /root directory- Shutdown the linux server: shutdown –h now

XIP Implementation


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XIP Implementation

The Process (Continued)- Define the DCSS: defseg netsnmp 20000-23fff sr

- Failed: The virtual machine didn’t have CP class E- Could have been done from some place like MAINT- Due to the amount of testing, gave the virtual machine class E

- Save the DCSS: saveseg netsnmp- Failed: The virtual machine size wasn’t large enough- Increased virtual storage: def stor 1024m- This causes a “system reset” so re-ipled CMS then re-issued the saveseg netsnmp- Side effect: PAGE space utilization shot way up

- Reboot LINUX


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XIP Implementation

Process (continued)- Build the list of files for overmounting: xip-howto-scripts/copylibs.sh –f snmpd –d

/dcss- Calculate the required DCSS space: du –sk /dcss

- This was actually done prior to creating the DCSS

- Determine the number of files that are going into the DCSS: find /dcss –print | wc -l- This was done to obtain overhead - approximately 4k per file- Guess what … it all fit in 64 meg

- Copy the init script to /sbin: cp /root/xip-howto-scripts/xipinit-fw.sh /sbin/xipinit –fw

- This test was for “file sharing” so we used the xipinit-fw.sh script instead of xipinit.sh script

- Alter the xipinit-fw.sh script to point to the mount point and recognize the DCSS name- Vi /sbin/xipinit-fw- #mount point of xipimage- MPXIPIMAGE=“/xip”- #name of xipimage- XIPIMAGE=“NETSNMP”


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XIP Implementation

Process (continued)- Load the DCSS driver: modprob dcssblk- Get the major number of dcssblk: cat /proc/devices- Check if devices were created: ls –l /dev/dcss*- First time through they probably aren’t so: mknod /dev/dcssblk0 b 252 0

- Do this for each “device” you want within the DCSS

- Load the DCSS: echo “NETSNMP” > /sys/devices/dcssblk/add- This failed because the memory was not adjusted to encompass the DCSS

- Change the zipl.conf file to define the memory: parameters = “root=/dev/dasda1 selinux=0 TERM=dump elevator=cfg mem=576M”

- Danger Will Robinson!!- Encountered trouble with mem=2G, so used mem=2047M

- Reboot Linux


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XIP Implementation

Process (continued)- Load the DCSS driver: modprob dcssblk- Load the DCSS: echo ‘NETSNMP” > /sys/devices/dcssblk/add

- Results are echoed onto the virtual console

- Set the DCSS for exclusive use: echo 0 > /sys/devices/dcssblk/NETSNMP/shared- Put the ext2 file system on a DCSS mapped device: mke2fs –b 4096

/dev/dcssblk0- Mount the device: mount /dev/dcssblk0 /mnt- Copy the files: cp –va /dcss/* /mnt- Save the DCSS: echo 1 > /sys/devices/dcssblk/NETSNMP/save- Unmount the DCSS: umount /mnt

- This is required to finalize the save of the DCSS

- Remove the DCSS: echo “NETSNMP” > /sys/devices/dcssblk/remove


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XIP Implementation

Process (continued)- Change kernel parms (zipl.conf) to init XIP.

- parameters = "root=/dev/dasda1 selinux=0 TERM=dumb elevator=cfq mem=576M init=/sbin/xipinit-fw"

- Shutdown Linux: shutdown –h now- Redefine virtual storage if necessary- Reboot LINUX


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Targeting

Identify large processesIdentify frequently used processesEliminate non-shareable processes


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Targeting Storage Processes


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Targeting Storage Processes


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Targeting Frequent Processes


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Targeting Frequent Processes


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LINUX Evaluation

Establish Base- Two Suse servers

- Each defined as 256M

- Base is no DCSS sharing


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LINUX Evaluation

Test 1- Two SUSE servers


- SUSELNX1 has a 16M DCSS at the 1.5G mark, mem=1556M

- SUSELNX2 has no DCSS

- Note Storage usage


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LINUX Evaluation

Test 2- Two Suse servers


- Each has a 16M DCSS at the 1.5G mark, mem=1556M



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LINUX Evaluation



- Each has a 16M DCSS at the 1G mark, mem=1040M



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LINUX Evaluation



- Each has a 16M DCSS at the 256M mark, mem=272M



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LINUX Evaluation

Back to base- Note Storage usage as compared to “TEST 4”


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z/VM Evaluation

VM Storage- Note resident pages as well as working set


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z/VM Evaluation

VM Storage- Note resident pages as well as working set


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More Testing

Case 2 – z/VM 5.1 SLES9 64-bit Virtual machine size – 2G DCSS defined in “storage hole” Moving 512M of Oracle 10g to DCSS Directory Sharing Results NYA (Watch for upcoming REDBOOK)


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Summary

Reduction in system storage requirements Increase in LINUX system storagepotential reduction in pagingReduction in disk space (DASD to us VMers)Benefits are best realized in installations

running many instances of LINUX with “common” functionality

Documents

Velocity Software, Inc - XIP for Linux1 XIP (eXecute In Place) for Linux on z/VM Implementation and Analysis [email protected] HTTP://VelocitySoftware.com