FWN/Beats/Virtualization

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{{Anchor|Virtualization}}
 
{{Anchor|Virtualization}}
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== Virtualization ==
 
== Virtualization ==
 
In this section, we cover discussion of Fedora virtualization technologies on the
 
In this section, we cover discussion of Fedora virtualization technologies on the
@fedora-virt and @libvirt-list lists.
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@fedora-virt list.
  
 
Contributing Writer: [[User:Dale | Dale Bewley]]
 
Contributing Writer: [[User:Dale | Dale Bewley]]
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[http://www.redhat.com/mailman/listinfo/fedora-virt fedora-virt list].
 
[http://www.redhat.com/mailman/listinfo/fedora-virt fedora-virt list].
  
==== KSM Tuning in Fedora 12 ====
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==== Virt Status Report ====
[[MarkMcLoughlin|Mark McLoughlin]]
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described<ref>http://www.redhat.com/archives/fedora-virt/2009-October/msg00119.html</ref>
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the default state of KSM<ref>http://fedoraproject.org/wiki/Features/KSM</ref> on Fedora systems.
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"For Fedora 13, it'll be off by default in the kernel and the recommended
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way of switching it on is with 'chkconfig ksm on'"
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"For Fedora [[Releases/12|12]], it's on by default in the kernel, 'chkconfig ksm on' just changes max pages and the only way of disabling it is by manually
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writing zero to {{filename|/sys/kernel/mm/ksm/run}}."
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At release of Fedora 12 the kernel will default to a maximum of 2000 merged memory pages. A future F12 kernel update to 2.6.32 will likely disable KSM by default.
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To take advantage of KSM in Fedora 12, the <code>ksm</code> service must be enabled:
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<pre>
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sudo chkconfig ksm on
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</pre>
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[[MarkMcLoughlin|Mark McLoughlin]]
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also noted<ref>http://www.redhat.com/archives/fedora-virt/2009-October/msg00112.html</ref>
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The maximum number of pages which may be merged defaults to half of the system
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memory, and may also be manually defined in {{filename|/etc/sysconfig/ksm}}.
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"Here's the logic we have in the init script<ref>http://gitorious.org/ksm-control-scripts/ksm-control-scripts</ref>:"
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<pre>
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  # unless KSM_MAX_KERNEL_PAGES is set, let ksm munch up to half of total memory.
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  default_max_kernel_pages () {
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      local total pagesize
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      total=`awk '/^MemTotal:/ {print $2}' /proc/meminfo`
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      pagesize=`getconf PAGESIZE`
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      echo $[total * 1024 / pagesize / 2]
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  }
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</pre>
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[[JustinForbes|Justin Forbes]]
 
[[JustinForbes|Justin Forbes]]
points out<ref>http://www.redhat.com/archives/fedora-virt/2009-October/msg00115.html</ref>
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posted<ref>http://www.redhat.com/archives/fedora-virt/2009-December/msg00056.html</ref> a Fedora virtualization status report.  
"The limit to half of total memory is because ksm pages are unswappable at
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Justin pointed out F13 bugs<ref>http://fedoraproject.org/wiki/Virtualization_bugs</ref> now include Important and Pony classifications in addition to Blocker and Target.
this time.  To be fixed in a future kernel."
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A second service, <code>ksmtuned</code>, may also be enabled.
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Ksmtuned regulates how aggressively the system will attempt to merge pages.
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Parameters such as how many pages to scan before sleeping and how long to
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sleep may be configured in {{filename|/etc/ksmtuned.conf}}.
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Memory pages must be flagged as mergable before KSM will scan them looking for
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duplicates. At present only Qemu pages will be marked as such.
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As described in the kernel docs<ref>http://www.kernel.org/doc/Documentation/vm/ksm.txt</ref>,
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the effect of KSM system memory may be examined in {{filename|/sys/kernel/mm/ksm}}.
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"A high ratio of pages_sharing to pages_shared indicates good sharing, but
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a high ratio of pages_unshared to pages_sharing indicates wasted effort."
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<references />
 
<references />
  
=== Libvirt List ===
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==== RHEL and Fedora Virtualization Feature Parity ====
This section contains the discussion happening on the
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Robert Day wondered how the virtualization features<ref>http://www.redhat.com/virtualization/rhev/</ref> of Red Hat Enterprise Linux 5.4
[http://www.redhat.com/mailman/listinfo/libvir-list libvir-list].
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compared to Fedora 12.
  
==== Rewrite the QEMU monitor handling ====
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[[DanielBerrange|Daniel Berrange]]  
[[DanielBerrange|Daniel Berrange]]
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explained<ref>http://www.redhat.com/archives/fedora-virt/2009-December/msg00040.html</ref>
posted<ref>http://www.redhat.com/archives/libvir-list/2009-October/msg00644.html</ref> a
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"The KVM based virtualization in RHEL-5.4 is not nearly so far behind
"patch series [which] rewrites the QEMU monitor handling almost completely.
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Fedora as you might think. The {{package|libvirt}} mgmt stack in RHEL-5.4 was
 
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rebased to be near parity with [[Releases/11|Fedora 11]], and KVM in RHEL-5.4 is
The key theme here is to move from a totally synchronous way of
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also pretty close to that using what's best described as a hybrid of
interacting with the monitor, to a totally asynchronous way. This
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kvm-83 and kvm-84."
allows " {{package|libvirt}} " to handle receipt & dispatch of asychronous events from
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QEMU. For example a notification of a disk-full error, or VM state
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change.  In the process of doing this re-factoring I have also
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dropped in basic support/infrastructure for the JSON based monitor."
+
  
 
<references />
 
<references />
  
==== Node device enumeration with udev ====
 
[[DaveAllan|Dave Allan]]
 
posted<ref>http://www.redhat.com/archives/libvir-list/2009-October/msg00731.html</ref>
 
"a fully functional version of the node device udev<ref>http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html</ref> based backend, incorporating all the feedback from earlier revisions." "...I have also included a patch removing the DevKit backend."
 
  
Also see FWN#146 <ref>http://fedoraproject.org/wiki/FWN/Issue146#Host_Device_Enumeration_API</ref> for some coverage of the host device enumeration API.
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====  ====
 +
<references />
  
 +
====  ====
 
<references />
 
<references />

Latest revision as of 18:09, 18 December 2009



Contents

[edit] Virtualization

In this section, we cover discussion of Fedora virtualization technologies on the @fedora-virt list.

Contributing Writer: Dale Bewley

[edit] Fedora Virtualization List

This section contains the discussion happening on the fedora-virt list.

[edit] Virt Status Report

Justin Forbes posted[1] a Fedora virtualization status report. Justin pointed out F13 bugs[2] now include Important and Pony classifications in addition to Blocker and Target.

  1. http://www.redhat.com/archives/fedora-virt/2009-December/msg00056.html
  2. http://fedoraproject.org/wiki/Virtualization_bugs

[edit] RHEL and Fedora Virtualization Feature Parity

Robert Day wondered how the virtualization features[1] of Red Hat Enterprise Linux 5.4 compared to Fedora 12.

Daniel Berrange explained[2] "The KVM based virtualization in RHEL-5.4 is not nearly so far behind Fedora as you might think. The Package-x-generic-16.pnglibvirt mgmt stack in RHEL-5.4 was rebased to be near parity with Fedora 11, and KVM in RHEL-5.4 is also pretty close to that using what's best described as a hybrid of kvm-83 and kvm-84."

  1. http://www.redhat.com/virtualization/rhev/
  2. http://www.redhat.com/archives/fedora-virt/2009-December/msg00040.html


[edit]


[edit]