The 4-patch series to follow this email extends KVM-hypervisor and Linux guest running on KVM-hypervisor to support pv-ticket spinlocks, based on Xen's implementation.
One hypercall is introduced in KVM hypervisor,that allows a vcpu to kick another vcpu out of halt state. The blocking of vcpu is done using halt() in (lock_spinning) slowpath. The V2 change discussion was in: https://lkml.org/lkml/2011/10/23/207 Previous discussions : (posted by Srivatsa V). https://lkml.org/lkml/2010/7/26/24 https://lkml.org/lkml/2011/1/19/212 The BASE patch is tip 3.2-rc1 + Jeremy's following patches. xadd (https://lkml.org/lkml/2011/10/4/328) x86/ticketlocklock (https://lkml.org/lkml/2011/10/12/496). Changes in V3: - rebased to 3.2-rc1 - use halt() instead of wait for kick hypercall. - modify kick hyper call to do wakeup halted vcpu. - hook kvm_spinlock_init to smp_prepare_cpus call (moved the call out of head##.c). - fix the potential race when zero_stat is read. - export debugfs_create_32 and add documentation to API. - use static inline and enum instead of ADDSTAT macro. - add barrier() in after setting kick_vcpu. - empty static inline function for kvm_spinlock_init. - combine the patches one and two readuce overhead. - make KVM_DEBUGFS depends on DEBUGFS. - include debugfs header unconditionally. Changes in V2: - rebased patchesto -rc9 - synchronization related changes based on Jeremy's changes (Jeremy Fitzhardinge <jeremy.fitzhardi...@citrix.com>) pointed by Stephan Diestelhorst <stephan.diestelho...@amd.com> - enabling 32 bit guests - splitted patches into two more chunks Srivatsa Vaddagiri, Suzuki Poulose, Raghavendra K T (4): Add debugfs support to print u32-arrays in debugfs Add a hypercall to KVM hypervisor to support pv-ticketlocks Added configuration support to enable debug information for KVM Guests pv-ticketlocks support for linux guests running on KVM hypervisor Results: From the results we can see that patched kernel performance is similar to BASE when there is no lock contention. But once we start seeing more contention, patched kernel outperforms BASE. set up : Kernel for host/guest : 3.2-rc1 + Jeremy's xadd, pv spinlock patches as BASE 3 guests with 8VCPU, 4GB RAM, 1 used for kernbench (kernbench -f -H -M -o 20) other for cpuhog (shell script while true with an instruction) scenario A: unpinned 1x: no hogs 2x: 8hogs in one guest 3x: 8hogs each in two guest Result for Non PLE machine : Machine : IBM xSeries with Intel(R) Xeon(R) x5570 2.93GHz CPU with 8 core , 64GB RAM BASE BASE+patch %improvement mean (sd) mean (sd) Scenario A: case 1x: 157.548 (10.624) 156.408 (11.1622) 0.723589 case 2x: 1110.18 (807.019) 310.96 (105.194) 71.9901 case 3x: 3110.36 (2408.03) 303.688 (110.474) 90.2362 Result for PLE machine: Machine : IBM xSeries with Intel(R) Xeon(R) X7560 2.27GHz CPU with 32/64 core, with 8 online cores and 4*64GB RAM BASE BASE+patch %improvement mean (sd) mean (sd) Scenario A: case 1x: 159.725 (47.4906) 159.07 (47.8133) 0.41008 case 2x: 190.957 (49.2976) 187.273 (50.5469) 1.92923 case 3x: 226.317 (88.6023) 223.698 (90.4362) 1.15723 --- 13 files changed, 454 insertions(+), 112 deletions(-) arch/x86/Kconfig | 9 ++ arch/x86/include/asm/kvm_para.h | 17 +++- arch/x86/kernel/kvm.c | 247 +++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/x86.c | 28 +++++- arch/x86/xen/debugfs.c | 104 ---------------- arch/x86/xen/debugfs.h | 4 - arch/x86/xen/spinlock.c | 2 +- fs/debugfs/file.c | 128 ++++++++++++++++++++ include/linux/debugfs.h | 11 ++ include/linux/kvm.h | 1 + include/linux/kvm_host.h | 5 + include/linux/kvm_para.h | 1 + virt/kvm/kvm_main.c | 7 + 13 files changed, 452 insertions(+), 112 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
