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| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2016-02-09 13:47:55 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-02-16 18:48:29 +0100 |
| commit | 6b6de68c63eda6240ec92e44b998f910156f8806 (patch) | |
| tree | bbac3e4b7e1ce1c9fdfef89b3fea0a04ad85e88e /virt | |
| parent | efef127c30c5ded4cb10fe36275d9b11d4633de4 (diff) | |
| download | linux-6b6de68c63eda6240ec92e44b998f910156f8806.tar.bz2 | |
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.c | 18 |
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); |