@@ -79,12 +79,13 @@ static inline void virtio_identify_template(struct virtio_blk_config *bc)
typedef struct VirtIOBlockReq
{
VirtIOBlock *dev;
- VirtQueueElement elem;
struct virtio_blk_inhdr *in;
struct virtio_blk_outhdr *out;
struct virtio_scsi_inhdr *scsi;
QEMUIOVector qiov;
struct VirtIOBlockReq *next;
+ /* Members that need clearing, must be added prior to elem */
+ VirtQueueElement elem;
} VirtIOBlockReq;
static void virtio_blk_req_complete(VirtIOBlockReq *req, int status)
@@ -139,7 +140,8 @@ static void virtio_blk_flush_complete(void *opaque, int ret)
static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
{
- VirtIOBlockReq *req = qemu_mallocz(sizeof(*req));
+ VirtIOBlockReq *req = qemu_malloc(sizeof(*req));
+ memset(req, 0, offsetof(VirtIOBlockReq, elem.in_addr[0]));
req->dev = s;
return req;
}
ok, Below is the patch. This time resent with mutt and hopefully without whitespace changes. -------------------------------------------------------------------- This patch reduces the amount of memory being cleared on every virtio-blk IO operation. Improve number of IOPS when using avirtio-blk device. On every virtio-blk IO command passed to QEMU, virtio_blk_alloc_request() allocates and clears (with qemu_mallocz()) a VirtIOBlockReq object. The sizeof(VirtIOBlockReq) equals 41040 bytes on my x86-64 machine. By moving the 'elem' variable to the end of VirtIOBlockReq and clearing only upto the address of the 'elem.in_addr' field, the memset() call now clears only 80 bytes. Signed-off-by: Saul Tamari <stamari@gmail.com> -------------------------------------------------