The commit is pushed to "branch-rh7-3.10.0-327.10.1.vz7.12.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.10.1.vz7.12.11
------>
commit 22631bc0045bcd5c83233b3c3194bc49d7681d78
Author: Christian Borntraeger <[email protected]>
Date: Tue Apr 19 14:22:52 2016 +0400
ms/kvm: halt_polling: improve grow/shrink settings
Right now halt_poll_ns can be change during runtime. The
grow and shrink factors can only be set during module load.
Lets fix several aspects of grow shrink:
- make grow/shrink changeable by root
- make all variables unsigned int
- read the variables once to prevent races
Signed-off-by: Christian Borntraeger <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
(cherry picked from commit 6b6de68c63eda6240ec92e44b998f910156f8806)
Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]>
---
include/trace/events/kvm.h | 9 +++++----
virt/kvm/kvm_main.c | 18 ++++++++++--------
2 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h
index 45afe07..4c05352 100644
--- a/include/trace/events/kvm.h
+++ b/include/trace/events/kvm.h
@@ -355,14 +355,15 @@ TRACE_EVENT(
);
TRACE_EVENT(kvm_halt_poll_ns,
- TP_PROTO(bool grow, unsigned int vcpu_id, int new, int old),
+ TP_PROTO(bool grow, unsigned int vcpu_id, unsigned int new,
+ unsigned int old),
TP_ARGS(grow, vcpu_id, new, old),
TP_STRUCT__entry(
__field(bool, grow)
__field(unsigned int, vcpu_id)
- __field(int, new)
- __field(int, old)
+ __field(unsigned int, new)
+ __field(unsigned int, old)
),
TP_fast_assign(
@@ -372,7 +373,7 @@ TRACE_EVENT(kvm_halt_poll_ns,
__entry->old = old;
),
- TP_printk("vcpu %u: halt_poll_ns %d (%s %d)",
+ TP_printk("vcpu %u: halt_poll_ns %u (%s %u)",
__entry->vcpu_id,
__entry->new,
__entry->grow ? "grow" : "shrink",
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 870c968..4cbac86 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -72,11 +72,11 @@ module_param(halt_poll_ns, uint, S_IRUGO | S_IWUSR);
/* Default doubles per-vcpu halt_poll_ns. */
static unsigned int halt_poll_ns_grow = 2;
-module_param(halt_poll_ns_grow, int, S_IRUGO);
+module_param(halt_poll_ns_grow, uint, S_IRUGO | S_IWUSR);
/* Default resets per-vcpu halt_poll_ns . */
static unsigned int halt_poll_ns_shrink;
-module_param(halt_poll_ns_shrink, int, S_IRUGO);
+module_param(halt_poll_ns_shrink, uint, S_IRUGO | S_IWUSR);
/*
* Ordering of locks:
@@ -1945,14 +1945,15 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_mark_page_dirty);
static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
{
- int old, val;
+ unsigned int old, val, grow;
old = val = vcpu->halt_poll_ns;
+ grow = READ_ONCE(halt_poll_ns_grow);
/* 10us base */
- if (val == 0 && halt_poll_ns_grow)
+ if (val == 0 && grow)
val = 10000;
else
- val *= halt_poll_ns_grow;
+ val *= grow;
vcpu->halt_poll_ns = val;
trace_kvm_halt_poll_ns_grow(vcpu->vcpu_id, val, old);
@@ -1960,13 +1961,14 @@ static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
static void shrink_halt_poll_ns(struct kvm_vcpu *vcpu)
{
- int old, val;
+ unsigned int old, val, shrink;
old = val = vcpu->halt_poll_ns;
- if (halt_poll_ns_shrink == 0)
+ shrink = READ_ONCE(halt_poll_ns_shrink);
+ if (shrink == 0)
val = 0;
else
- val /= halt_poll_ns_shrink;
+ val /= shrink;
vcpu->halt_poll_ns = val;
trace_kvm_halt_poll_ns_shrink(vcpu->vcpu_id, val, old);
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