Re: [kvm-devel] [patch 1/5] KVM: add basic paravirt support (v2)
Marcelo Tosatti wrote: Add basic KVM paravirt support. Avoid vm-exits on IO delays. Add KVM_GET_PARA_FEATURES ioctl so paravirt features can be reported in a single bitmask. This allows the host to disable features on runtime if appropriate, which would require one ioctl per feature otherwise. The limit of 32 features can be extended to 64 if needed, beyond that a new MSR is required. v1-v2: - replace KVM_CAP_CLOCKSOURCE with KVM_CAP_PARA_FEATURES - cover FEATURE_CLOCKSOURCE I don't understand the motivation for this. A handful of ioctl()s at init time are hardly time consuming. There is the advantage that paravirt kernel advances are reflected automatically without changes in userspace, but sometimes this is a disadvantage (it means there is no way to disable it, for instance). -- error compiling committee.c: too many arguments to function - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] [patch 1/5] KVM: add basic paravirt support (v2)
On Thu, Feb 21, 2008 at 05:38:30PM +0200, Avi Kivity wrote: Marcelo Tosatti wrote: Add basic KVM paravirt support. Avoid vm-exits on IO delays. Add KVM_GET_PARA_FEATURES ioctl so paravirt features can be reported in a single bitmask. This allows the host to disable features on runtime if appropriate, which would require one ioctl per feature otherwise. The limit of 32 features can be extended to 64 if needed, beyond that a new MSR is required. v1-v2: - replace KVM_CAP_CLOCKSOURCE with KVM_CAP_PARA_FEATURES - cover FEATURE_CLOCKSOURCE I don't understand the motivation for this. A handful of ioctl()s at init time are hardly time consuming. There is the advantage that paravirt kernel advances are reflected automatically without changes in userspace, but sometimes this is a disadvantage (it means there is no way to disable it, for instance). One ioctl per feature sounded like unnecessary code duplication. I have no problems with it though. So you prefer that way? - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] [patch 1/5] KVM: add basic paravirt support (v2)
Marcelo Tosatti wrote: One ioctl per feature sounded like unnecessary code duplication. I have no problems with it though. So you prefer that way? Yes. I think we can avoid code duplication. -- error compiling committee.c: too many arguments to function - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
