diff options
| author | Zhai, Edwin <edwin.zhai@intel.com> | 2009-10-09 18:03:20 +0800 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-12-03 09:32:17 +0200 |
| commit | 4b8d54f9726f1159330201c5ed2ea30bce7e63ea (patch) | |
| tree | 903eaf21f46359f3e42a6d4582ca792b73d4b7b9 /arch/x86/include | |
| parent | d255f4f2bac81eb798fcf76938147f1f6c756ae2 (diff) | |
KVM: VMX: Add support for Pause-Loop Exiting
New NHM processors will support Pause-Loop Exiting by adding 2 VM-execution
control fields:
PLE_Gap - upper bound on the amount of time between two successive
executions of PAUSE in a loop.
PLE_Window - upper bound on the amount of time a guest is allowed to execute in
a PAUSE loop
If the time, between this execution of PAUSE and previous one, exceeds the
PLE_Gap, processor consider this PAUSE belongs to a new loop.
Otherwise, processor determins the the total execution time of this loop(since
1st PAUSE in this loop), and triggers a VM exit if total time exceeds the
PLE_Window.
* Refer SDM volume 3b section 21.6.13 & 22.1.3.
Pause-Loop Exiting can be used to detect Lock-Holder Preemption, where one VP
is sched-out after hold a spinlock, then other VPs for same lock are sched-in
to waste the CPU time.
Our tests indicate that most spinlocks are held for less than 212 cycles.
Performance tests show that with 2X LP over-commitment we can get +2% perf
improvement for kernel build(Even more perf gain with more LPs).
Signed-off-by: Zhai Edwin <edwin.zhai@intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/vmx.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h index 272514c2d45..2b4945419a8 100644 --- a/arch/x86/include/asm/vmx.h +++ b/arch/x86/include/asm/vmx.h @@ -56,6 +56,7 @@ #define SECONDARY_EXEC_ENABLE_VPID 0x00000020 #define SECONDARY_EXEC_WBINVD_EXITING 0x00000040 #define SECONDARY_EXEC_UNRESTRICTED_GUEST 0x00000080 +#define SECONDARY_EXEC_PAUSE_LOOP_EXITING 0x00000400 #define PIN_BASED_EXT_INTR_MASK 0x00000001 @@ -144,6 +145,8 @@ enum vmcs_field { VM_ENTRY_INSTRUCTION_LEN = 0x0000401a, TPR_THRESHOLD = 0x0000401c, SECONDARY_VM_EXEC_CONTROL = 0x0000401e, + PLE_GAP = 0x00004020, + PLE_WINDOW = 0x00004022, VM_INSTRUCTION_ERROR = 0x00004400, VM_EXIT_REASON = 0x00004402, VM_EXIT_INTR_INFO = 0x00004404, @@ -248,6 +251,7 @@ enum vmcs_field { #define EXIT_REASON_MSR_READ 31 #define EXIT_REASON_MSR_WRITE 32 #define EXIT_REASON_MWAIT_INSTRUCTION 36 +#define EXIT_REASON_PAUSE_INSTRUCTION 40 #define EXIT_REASON_MCE_DURING_VMENTRY 41 #define EXIT_REASON_TPR_BELOW_THRESHOLD 43 #define EXIT_REASON_APIC_ACCESS 44 |