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hw/9pfs: Use ioeventfd for 9p 

With ioeventfd:
[root@qemu-img-64 storage]# dd if=/dev/zero of=/storage/testx bs=8k count=131072 oflag=direct
131072+0 records in
131072+0 records out
1073741824 bytes (1.1 GB) copied, 26.767 s, 40.1 MB/s

Without:
[root@qemu-img-64 storage]# dd if=/dev/zero of=/storage/testx bs=8k count=131072 oflag=direct
131072+0 records in
131072+0 records out
1073741824 bytes (1.1 GB) copied, 65.3361 s, 16.4 MB/s

Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
This commit is contained in:
Aneesh Kumar K.V 2011-10-12 19:11:23 +05:30
parent ebffe2afce
commit 5745e38afe
3 changed files with 7 additions and 5 deletions
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2
hw/9pfs/virtio-9p-device.c
View File

@ -169,6 +169,8 @@ static PCIDeviceInfo virtio_9p_info = {
.revision = VIRTIO_PCI_ABI_VERSION,
.class_id = 0x2,
.qdev.props = (Property[]) {
DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
DEFINE_PROP_STRING("mount_tag", VirtIOPCIProxy, fsconf.tag),

5
hw/virtio-pci.c
View File

@ -83,11 +83,6 @@
/* Flags track per-device state like workarounds for quirks in older guests. */
#define VIRTIO_PCI_FLAG_BUS_MASTER_BUG (1 << 0)
/* Performance improves when virtqueue kick processing is decoupled from the
* vcpu thread using ioeventfd for some devices. */
#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
#define VIRTIO_PCI_FLAG_USE_IOEVENTFD (1 << VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
/* QEMU doesn't strictly need write barriers since everything runs in
* lock-step. We'll leave the calls to wmb() in though to make it obvious for
* KVM or if kqemu gets SMP support.

5
hw/virtio-pci.h
View File

@ -18,6 +18,11 @@
#include "virtio-net.h"
#include "virtio-serial.h"
/* Performance improves when virtqueue kick processing is decoupled from the
* vcpu thread using ioeventfd for some devices. */
#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
#define VIRTIO_PCI_FLAG_USE_IOEVENTFD (1 << VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
typedef struct {
PCIDevice pci_dev;
VirtIODevice *vdev;