This document describes one way to created the rcu-test-image file that contains the filesystem used by the guest-OS kernel. There are probably much better ways of doing this, and this filesystem could no doubt be smaller. It is probably also possible to simply download an appropriate image from any number of places. That said, here are the commands: ------------------------------------------------------------------------ dd if=/dev/zero of=rcu-test-image bs=400M count=1 mkfs.ext3 ./rcu-test-image sudo mount -o loop ./rcu-test-image /mnt # Replace "precise" below with your favorite Ubuntu release. # Empirical evidence says this image will work for 64-bit, but... # Note that debootstrap does take a few minutes to run. Or longer. sudo debootstrap --verbose --arch i386 precise /mnt http://archive.ubuntu.com/ubuntu cat << '___EOF___' | sudo dd of=/mnt/etc/fstab # UNCONFIGURED FSTAB FOR BASE SYSTEM # /dev/vda / ext3 defaults 1 1 dev /dev tmpfs rw 0 0 tmpfs /dev/shm tmpfs defaults 0 0 devpts /dev/pts devpts gid=5,mode=620 0 0 sysfs /sys sysfs defaults 0 0 proc /proc proc defaults 0 0 ___EOF___ sudo umount /mnt ------------------------------------------------------------------------ References: http://sripathikodi.blogspot.com/2010/02/creating-kvm-bootable-fedora-system.html https://help.ubuntu.com/community/KVM/CreateGuests https://help.ubuntu.com/community/JeOSVMBuilder http://wiki.libvirt.org/page/UbuntuKVMWalkthrough http://www.moe.co.uk/2011/01/07/pci_add_option_rom-failed-to-find-romfile-pxe-rtl8139-bin/ -- "apt-get install kvm-pxe" http://www.landley.net/writing/rootfs-howto.html http://en.wikipedia.org/wiki/Initrd http://en.wikipedia.org/wiki/Cpio http://wiki.libvirt.org/page/UbuntuKVMWalkthrough href='/cgit.cgi/linux/net-next.git/diff/net/llc?id=6e978b22efa1db9f6e71b24440b5f1d93e968ee3'>diff
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authorSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>2017-02-03 14:18:39 -0800
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-02-04 00:11:08 +0100
commit6e978b22efa1db9f6e71b24440b5f1d93e968ee3 (patch)
treec666f7a26b860674848949e39a610222b0723f89 /net/llc
parent3c223c19aea85d3dda1416c187915f4a30b04b1f (diff)
cpufreq: intel_pstate: Disable energy efficiency optimization
Some Kabylake desktop processors may not reach max turbo when running in HWP mode, even if running under sustained 100% utilization. This occurs when the HWP.EPP (Energy Performance Preference) is set to "balance_power" (0x80) -- the default on most systems. It occurs because the platform BIOS may erroneously enable an energy-efficiency setting -- MSR_IA32_POWER_CTL BIT-EE, which is not recommended to be enabled on this SKU. On the failing systems, this BIOS issue was not discovered when the desktop motherboard was tested with Windows, because the BIOS also neglects to provide the ACPI/CPPC table, that Windows requires to enable HWP, and so Windows runs in legacy P-state mode, where this setting has no effect. Linux' intel_pstate driver does not require ACPI/CPPC to enable HWP, and so it runs in HWP mode, exposing this incorrect BIOS configuration. There are several ways to address this problem. First, Linux can also run in legacy P-state mode on this system. As intel_pstate is how Linux enables HWP, booting with "intel_pstate=disable" will run in acpi-cpufreq/ondemand legacy p-state mode. Or second, the "performance" governor can be used with intel_pstate, which will modify HWP.EPP to 0. Or third, starting in 4.10, the /sys/devices/system/cpu/cpufreq/policy*/energy_performance_preference attribute in can be updated from "balance_power" to "performance". Or fourth, apply this patch, which fixes the erroneous setting of MSR_IA32_POWER_CTL BIT_EE on this model, allowing the default configuration to function as designed. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Reviewed-by: Len Brown <len.brown@intel.com> Cc: 4.6+ <stable@vger.kernel.org> # 4.6+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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