[Xen-devel] [PATCH RFC V2 0/5] kvm : Paravirt-spinlock support for KVM guests

[Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>]

The 5-patch series to follow this email extends KVM-hypervisor and Linux guest 
running on KVM-hypervisor to support pv-ticket spinlocks, based heavily on 
Xen's implementation.

Two hypercalls are being introduced in KVM hypervisor, one that allows a
vcpu (spinning on a lock) to block and another that allows a vcpu to kick
another out of blocking state.

This is discussed in : (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 rc9 + Jeremy's following patches.
compare exchange (https://lkml.org/lkml/2011/8/29/321), 
xadd (https://lkml.org/lkml/2011/10/4/328)
x86/ticketlocklock  (https://lkml.org/lkml/2011/10/12/496).

Changes since last posting:
- rebased patchesto -rc9
- synchronization related changes based on Jeremy's changes (Jeremy 
Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>) pointed by
Stephan Diestelhorst <stephan.diestelhorst@xxxxxxx>
- enabling 32 bit guests
- splitted patches into two more chunks

Results:

set up : 
Kernel for host/guest : 3.1-rc9 + Jeremys ticketlock cleanup, 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
scenario B: each vcpu pinned to corresponding cpu

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:         157.495 (15.2924)       148.355 (7.35479)      5.80336
case 2x:         761.955 (581.384)       247.306 (64.4707)      67.5432
case 3x:         2804.36 (2613.57)       261.522 (85.0856)      90.6744

Scenario B                              
case 1x:         1241.86 (812.155)       313.805 (140.99)       74.731
case 2x:         1277.32 (771.316)       308.325 (124.808)      75.8616
case 3x:         1239.45 (860.012)       307.535 (124.243)      75.1878

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:         72.7133 (43.7109)       70.0734 (37.7866)      3.63056
case 2x:         124.138 (79.9515)       119.28 (81.3597)       3.91339
case 3x:         174.561 (132.209)       159.283 (116.232)      8.75224

Scenario B                              
case 1x:         166.101 (119.313)       160.056 (117.446)      3.63935
case 2x:         167.421 (120.767)       158.133 (115.022)      5.54769
case 3x:         169.317 (122.088)       159.353 (116.737)      5.88482

 Srivatsa Vaddagiri, Suzuki Poulose, Raghavendra K T (5): 
  Add debugfs support to print u32-arrays in debugfs
  Renaming of xen functions and change unsigned to u32
  Add two hypercalls 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
 
 arch/x86/Kconfig                |    9 ++
 arch/x86/include/asm/kvm_para.h |   12 ++-
 arch/x86/kernel/head32.c        |    3 +
 arch/x86/kernel/head64.c        |    3 +
 arch/x86/kernel/kvm.c           |  247 +++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/x86.c              |   67 +++++++++++-
 arch/x86/xen/debugfs.c          |  104 ----------------
 arch/x86/xen/debugfs.h          |    4 -
 arch/x86/xen/spinlock.c         |    2 +-
 fs/debugfs/file.c               |  108 +++++++++++++++++
 include/linux/debugfs.h         |   11 ++
 include/linux/kvm.h             |    1 +
 include/linux/kvm_host.h        |    5 +
 include/linux/kvm_para.h        |    2 +
 virt/kvm/kvm_main.c             |    1 +
 15 files changed, 468 insertions(+), 111 deletions(-)
---

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