FWN/Beats/Virtualization

From FedoraProject

< FWN | Beats(Difference between revisions)
Jump to: navigation, search
(→‎Libvirt List)
(starting next ed)
Line 13: Line 13:
 
[http://www.redhat.com/mailman/listinfo/fedora-virt fedora-virt list].
 
[http://www.redhat.com/mailman/listinfo/fedora-virt fedora-virt list].
  
−
==== Fedora Virt Status ====
+
==== Bridges ====
−
[[MarkMcLoughlin|Mark McLoughlin]]
+
[[AndrésGarcía|Andrés García]]
−
posted<ref>http://www.redhat.com/archives/fedora-virt/2009-October/msg00138.html</ref>
+
asked<ref>http://www.redhat.com/archives/fedora-virt/2009-November/msg00002.html</ref>
−
another excellent round up of virt related bugs and developments. Mark reports
+
−
"Thankfully, the virt blocker list is now clear, but if you're looking
+
−
to help with making Fedora 12 even better, there's no better place to
+
−
start than the F12 target tracker bug<ref>https://bugzilla.redhat.com/showdependencytree.cgi?id=F12VirtTarget&hide_resolved=1</ref>:
+
  
−
There's over 100 bugs there that need your help!"
+
<ref>http://wiki.libvirt.org/page/Networking#Bridged_networking_.28aka_.22shared_physical_device.22.29</ref>
  
−
<references />
+
<ref>https://fedorahosted.org/netcf/</ref>
−
 
+
<ref>http://linux-kvm.com/content/netcf-silver-bullet-network-configuration</ref>
−
==== Help testing the Windows Registry feature of libguestfs ====
+
−
[[RichardJones|Richard Jones]]
+
−
asked<ref>http://www.redhat.com/archives/fedora-virt/2009-October/msg00128.html</ref> for some help testing a new feature of {{package|libguestfs}}
+
−
 
+
−
"If you have any Windows guests, then you can help Fedora to support
+
−
Windows guests better by spending a few minutes testing the Windows
+
−
Registry feature we just added to libguestfs 1.0.75."
+
−
 
+
−
To help, all you need is:
+
−
* A Windows NT/200x/XP/Vista/7/... guest
+
−
* Fedora 12 or Fedora Rawhide host
+
−
* <code>libguestfs-tools</code> >= 1.0.75 (from updates or koji<ref>http://koji.fedoraproject.org/koji/packageinfo?packageID=8391</ref>)
+
−
* a few minutes of your time
+
−
 
+
−
<references />
+
−
 
+
−
==== KSM Tuning in Fedora 12 ====
+
−
[[MarkMcLoughlin|Mark McLoughlin]]
+
−
described<ref>http://www.redhat.com/archives/fedora-virt/2009-October/msg00119.html</ref>
+
−
the default state of KSM<ref>http://fedoraproject.org/wiki/Features/KSM</ref> on Fedora systems.
+
−
"For Fedora 13, it'll be off by default in the kernel and the recommended
+
−
way of switching it on is with 'chkconfig ksm on'"
+
−
"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
+
−
writing zero to {{filename|/sys/kernel/mm/ksm/run}}."
+
−
 
+
−
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.
+
−
To take advantage of KSM in Fedora 12, the <code>ksm</code> service must be enabled:
+
−
<pre>
+
−
sudo chkconfig ksm on
+
−
</pre>
+
−
 
+
−
[[MarkMcLoughlin|Mark McLoughlin]]
+
−
also noted<ref>http://www.redhat.com/archives/fedora-virt/2009-October/msg00112.html</ref>
+
−
The maximum number of pages which may be merged defaults to half of the system
+
−
memory, and may also be manually defined in {{filename|/etc/sysconfig/ksm}}.
+
−
"Here's the logic we have in the init script<ref>http://gitorious.org/ksm-control-scripts/ksm-control-scripts</ref>:"
+
−
<pre>
+
−
  # unless KSM_MAX_KERNEL_PAGES is set, let ksm munch up to half of total memory.
+
−
  default_max_kernel_pages () {
+
−
      local total pagesize
+
−
      total=`awk '/^MemTotal:/ {print $2}' /proc/meminfo`
+
−
      pagesize=`getconf PAGESIZE`
+
−
      echo $[total * 1024 / pagesize / 2]
+
−
  }
+
−
</pre>
+
−
 
+
−
[[JustinForbes|Justin Forbes]]
+
−
points out<ref>http://www.redhat.com/archives/fedora-virt/2009-October/msg00115.html</ref>
+
−
"The limit to half of total memory is because ksm pages are unswappable at
+
−
this time.  To be fixed in a future kernel."
+
−
 
+
−
A second service, <code>ksmtuned</code>, may also be enabled.
+
−
Ksmtuned regulates how aggressively the system will attempt to merge pages.
+
−
Parameters such as how many pages to scan before sleeping and how long to
+
−
sleep may be configured in {{filename|/etc/ksmtuned.conf}}.
+
−
 
+
−
Memory pages must be flagged as mergable before KSM will scan them looking for
+
−
duplicates. At present only Qemu pages will be marked as such.
+
−
As described in the kernel docs<ref>http://www.kernel.org/doc/Documentation/vm/ksm.txt</ref>,
+
−
the effect of KSM system memory may be examined in {{filename|/sys/kernel/mm/ksm}}.
+
−
"A high ratio of pages_sharing to pages_shared indicates good sharing, but
+
−
a high ratio of pages_unshared to pages_sharing indicates wasted effort."
+
  
 
<references />
 
<references />

Revision as of 22:03, 8 November 2009


Contents

Virtualization

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

Contributing Writer: Dale Bewley

Fedora Virtualization List

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

Bridges

Andrés García asked[1]

[2]

[3] [4]

  1. ↑ http://www.redhat.com/archives/fedora-virt/2009-November/msg00002.html
  2. ↑ http://wiki.libvirt.org/page/Networking#Bridged_networking_.28aka_.22shared_physical_device.22.29
  3. ↑ https://fedorahosted.org/netcf/
  4. ↑ http://linux-kvm.com/content/netcf-silver-bullet-network-configuration

Libvirt List

This section contains the discussion happening on the libvir-list.

Node device enumeration with udev

Dave Allan posted[1] "a fully functional version of the node device udev[2] based backend, incorporating all the feedback from earlier revisions." "...I have also included a patch removing the DevKit backend."

Also see FWN#146 "Host Device Enumeration API"[3] for some coverage of the host device enumeration API.

  1. ↑ http://www.redhat.com/archives/libvir-list/2009-October/msg00731.html
  2. ↑ http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html
  3. ↑ http://fedoraproject.org/wiki/FWN/Issue146#Host_Device_Enumeration_API

Rewrite of QEMU monitor handling

Daniel Berrange posted[1] a "patch series [which] rewrites the QEMU monitor handling almost completely.

The key theme here is to move from a totally synchronous way of interacting with the monitor, to a totally asynchronous way. This allows " Package-x-generic-16.pnglibvirt " to handle receipt & dispatch of asychronous events from QEMU. For example a notification of a disk-full error, or VM state change. In the process of doing this re-factoring I have also dropped in basic support/infrastructure for the JSON based monitor."

  1. ↑ http://www.redhat.com/archives/libvir-list/2009-October/msg00644.html

Libvirt QEMU driver thread safety rules

In a characteristically long and detailed post Daniel Berrange laid[1] donw the law on thread safety rules for the Qemu driver[2].

"This document describes how thread safety is ensured throughout the QEMU driver. The criteria for this model are:

  • Objects must never be exclusively locked for any pro-longed time
  • Code which sleeps must be able to time out after suitable period
  • Must be safe against dispatch asynchronous events from monitor"

Also see FWN#155 "Thread Safety for libvirtd Daemon and Drivers"[3]

  1. ↑ http://www.redhat.com/archives/libvir-list/2009-October/msg00815.html
  2. ↑ http://www.libvirt.org/drvqemu.html
  3. ↑ http://fedoraproject.org/wiki/FWN/Issue155#Thread_Safety_for_libvirtd_Daemon_and_Drivers
Retrieved from "https://fedoraproject.org/w/index.php?title=FWN/Beats/Virtualization&oldid=134946"