On 01/06/2011 12:10 PM, Zachary Amsden wrote:
Reasons to trap the TSC are numerous, but we want to avoid it as much as possible for performance reasons. We provide two conservative modes via modules parameters and userspace hinting. First, the module can be loaded with "tsc_auto=1" as a module parameter, which turns on conservative TSC trapping only when it is required (when unstable TSC or faster KHZ CPU is detected). For userspace hinting, we enable trapping only if necessary. Userspace can hint that a VM needs a fixed frequency TSC, and also that SMP stability will be required. In that case, we conservatively turn on trapping when it is needed. In addition, users may now specify the desired TSC rate at which to run. If this rate differs significantly from the host rate, trapping will be enabled. There is also an override control to allow TSC trapping to be turned on or off unconditionally for testing. We indicate to pvclock users that the TSC is being trapped, to allow avoiding overhead and directly using RDTSCP (only for SVM). This optimization is not yet implemented. Signed-off-by: Zachary Amsden<zamsden@xxxxxxxxxx> --- arch/x86/include/asm/kvm_host.h | 6 +- arch/x86/include/asm/pvclock-abi.h | 1 + arch/x86/kvm/svm.c | 20 ++++++ arch/x86/kvm/vmx.c | 21 +++++++ arch/x86/kvm/x86.c | 113 +++++++++++++++++++++++++++++++++--- arch/x86/kvm/x86.h | 2 + include/linux/kvm.h | 15 +++++ 7 files changed, 168 insertions(+), 10 deletions(-)
Haven't reviewed yet, but Documentation/kvm/api.txt is missing here. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
