This patch reduces the size of memory being cleared on every virtio-blk IO. On every virtio-blk IO 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 <st...@xxxxxxxxx> --- diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c index 2630b99..fd44371 100644 --- a/hw/virtio-blk.c +++ b/hw/virtio-blk.c @@ -79,12 +79,12 @@ 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; + VirtQueueElement elem; } VirtIOBlockReq; static void virtio_blk_req_complete(VirtIOBlockReq *req, int status) @@ -139,7 +139,8 @@ 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, (size_t)&(((VirtIOBlockReq*)0)->elem.in_addr[0])); req->dev = s; return req; } -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html