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authorJason Wang <jasowang@redhat.com>2015-06-04 05:28:46 -0400
committerMichael S. Tsirkin <mst@redhat.com>2015-06-04 12:44:49 +0200
commit309750fad51f17d1ec6195c5d8ad7d741596ddb6 (patch)
treecc12aaf687a92a9d35870700035234e10dd6791c /include/hw
parent6e7d82497dc8da7d420c8fa6632d759e08a18bc3 (diff)
vhost: logs sharing
Currently we allocate one vhost log per vhost device. This is sub optimal when: - Guest has several device with vhost as backend - Guest has multiqueue devices In the above cases, we can avoid the memory allocation by sharing a single vhost log among all the vhost devices. This is done through: - Introducing a new vhost_log structure with refcnt inside. - Using a global pointer to vhost_log structure that will be used. And introduce helper to get the log with expected log size and helper to - drop the refcnt to the old log. - Each vhost device still keep track of a pointer to the log that was used. With above, if no resize happens, all vhost device will share a single vhost log. During resize, a new vhost_log structure will be allocated and made for the global pointer. And each vhost devices will drop the refcnt to the old log. Tested by doing scp during migration for a 2 queues virtio-net-pci. Cc: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'include/hw')
-rw-r--r--include/hw/virtio/vhost.h8
1 files changed, 7 insertions, 1 deletions
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 8f04888e72..816a2e8db2 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -28,6 +28,12 @@ typedef unsigned long vhost_log_chunk_t;
#define VHOST_LOG_CHUNK (VHOST_LOG_PAGE * VHOST_LOG_BITS)
#define VHOST_INVALID_FEATURE_BIT (0xff)
+struct vhost_log {
+ unsigned long long size;
+ int refcnt;
+ vhost_log_chunk_t log[0];
+};
+
struct vhost_memory;
struct vhost_dev {
MemoryListener memory_listener;
@@ -43,7 +49,6 @@ struct vhost_dev {
unsigned long long backend_features;
bool started;
bool log_enabled;
- vhost_log_chunk_t *log;
unsigned long long log_size;
Error *migration_blocker;
bool force;
@@ -52,6 +57,7 @@ struct vhost_dev {
hwaddr mem_changed_end_addr;
const VhostOps *vhost_ops;
void *opaque;
+ struct vhost_log *log;
};
int vhost_dev_init(struct vhost_dev *hdev, void *opaque,