On 07/15/2011 02:37 PM, Sasha Levin wrote:
Move the check whether there are available entries to within the spinlock.
This allows working with larger amount of VCPUs and reduces premature
exits when using a large number of VCPUs.
Cc: Avi Kivity<[email protected]>
Cc: Ingo Molnar<[email protected]>
Cc: Marcelo Tosatti<[email protected]>
Cc: Pekka Enberg<[email protected]>
Signed-off-by: Sasha Levin<[email protected]>
---
virt/kvm/coalesced_mmio.c | 9 ++++++---
1 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index fc84875..34188db 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -37,7 +37,7 @@ static int coalesced_mmio_in_range(struct
kvm_coalesced_mmio_dev *dev,
*/
ring = dev->kvm->coalesced_mmio_ring;
avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
- if (avail< KVM_MAX_VCPUS) {
+ if (avail == 0) {
/* full */
return 0;
}
@@ -63,11 +63,14 @@ static int coalesced_mmio_write(struct kvm_io_device *this,
{
struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
- if (!coalesced_mmio_in_range(dev, addr, len))
- return -EOPNOTSUPP;
spin_lock(&dev->lock);
+ if (!coalesced_mmio_in_range(dev, addr, len)) {
+ spin_unlock(&dev->lock);
+ return -EOPNOTSUPP;
+ }
+
/* copy data in first free entry of the ring */
Hmm. This means we take the lock for every I/O, whether it hits
coalesced mmio or not.
We need to do the range check before taking the lock and the space check
after taking the lock.
--
error compiling committee.c: too many arguments to function
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