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KVM: disable halt_poll_ns as default for s390x 

We observed some performance degradation on s390x with dynamic
halt polling. Until we can provide a proper fix, let's enable
halt_poll_ns as default only for supported architectures.

Architectures are now free to set their own halt_poll_ns
default value.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
hifive-unleashed-5.1
David Hildenbrand 2015-09-18 12:34:53 +02:00 committed by Paolo Bonzini
parent 58c95070da
commit 920552b213
7 changed files with 8 additions and 2 deletions
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1
arch/arm/include/asm/kvm_host.h
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@ -33,6 +33,7 @@
#define KVM_PRIVATE_MEM_SLOTS 4
#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
#define KVM_HAVE_ONE_REG
#define KVM_HALT_POLL_NS_DEFAULT 500000
#define KVM_VCPU_MAX_FEATURES 2

1
arch/arm64/include/asm/kvm_host.h
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@ -33,6 +33,7 @@
#define KVM_USER_MEM_SLOTS 32
#define KVM_PRIVATE_MEM_SLOTS 4
#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
#define KVM_HALT_POLL_NS_DEFAULT 500000
#include <kvm/arm_vgic.h>
#include <kvm/arm_arch_timer.h>

1
arch/mips/include/asm/kvm_host.h
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@ -61,6 +61,7 @@
#define KVM_PRIVATE_MEM_SLOTS 0
#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
#define KVM_HALT_POLL_NS_DEFAULT 500000

1
arch/powerpc/include/asm/kvm_host.h
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@ -44,6 +44,7 @@
#ifdef CONFIG_KVM_MMIO
#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
#endif
#define KVM_HALT_POLL_NS_DEFAULT 500000
/* These values are internal and can be increased later */
#define KVM_NR_IRQCHIPS 1

1
arch/s390/include/asm/kvm_host.h
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@ -35,6 +35,7 @@
*/
#define KVM_NR_IRQCHIPS 1
#define KVM_IRQCHIP_NUM_PINS 4096
#define KVM_HALT_POLL_NS_DEFAULT 0
#define SIGP_CTRL_C 0x80
#define SIGP_CTRL_SCN_MASK 0x3f

1
arch/x86/include/asm/kvm_host.h
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@ -40,6 +40,7 @@
#define KVM_PIO_PAGE_OFFSET 1
#define KVM_COALESCED_MMIO_PAGE_OFFSET 2
#define KVM_HALT_POLL_NS_DEFAULT 500000
#define KVM_IRQCHIP_NUM_PINS KVM_IOAPIC_NUM_PINS

4
virt/kvm/kvm_main.c
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@ -66,8 +66,8 @@
MODULE_AUTHOR("Qumranet");
MODULE_LICENSE("GPL");
/* halt polling only reduces halt latency by 5-7 us, 500us is enough */
static unsigned int halt_poll_ns = 500000;
/* Architectures should define their poll value according to the halt latency */
static unsigned int halt_poll_ns = KVM_HALT_POLL_NS_DEFAULT;
module_param(halt_poll_ns, uint, S_IRUGO | S_IWUSR);
/* Default doubles per-vcpu halt_poll_ns. */