Ming Lei <ming.lei@xxxxxxxxxxxxx> writes: > Firstly, it isn't necessary to hold lock of vblk->vq_lock > when notifying hypervisor about queued I/O. > > Secondly, virtqueue_notify() will cause world switch and > it may take long time on some hypervisors(such as, qemu-arm), > so it isn't good to hold the lock and block other vCPUs. > > On arm64 quad core VM(qemu-kvm), the patch can increase I/O > performance a lot with VIRTIO_RING_F_EVENT_IDX enabled: > - without the patch: 14K IOPS > - with the patch: 34K IOPS > > fio script: > [global] > direct=1 > bsrange=4k-4k > timeout=10 > numjobs=4 > ioengine=libaio > iodepth=64 > > filename=/dev/vdc > group_reporting=1 > > [f1] > rw=randread > > Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx> > Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx> > Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx> Acked-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx> Thanks! Rusty. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
