summaryrefslogtreecommitdiff
path: root/virt
diff options
context:
space:
mode:
authorChristian Borntraeger <borntraeger@de.ibm.com>2016-02-09 13:47:55 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2016-02-16 18:48:29 +0100
commit6b6de68c63eda6240ec92e44b998f910156f8806 (patch)
treebbac3e4b7e1ce1c9fdfef89b3fea0a04ad85e88e /virt
parentefef127c30c5ded4cb10fe36275d9b11d4633de4 (diff)
downloadlinux-6b6de68c63eda6240ec92e44b998f910156f8806.tar.gz
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 <borntraeger@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c18
1 files changed, 10 insertions, 8 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a11cfd20a6a0..ba45e41c3210 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:
@@ -1943,14 +1943,15 @@ 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);
@@ -1958,13 +1959,14 @@ 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);