| Message ID | 1437407656-26726-1-git-send-email-stefanha@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Mon, 07/20 16:54, Stefan Hajnoczi wrote: > The raw-posix block driver implements Linux AIO batching so multiple > requests can be submitted with a single io_submit(2) system call. > Batching is currently only used by virtio-scsi and > virtio-blk-data-plane. > > Enable batching for regular virtio-blk so the number of io_submit(2) > system calls is reduced for workloads with queue depth > 1. > > In 4KB random read performance tests with queue depth 32, the CPU > utilization on the host is reduced by 9.4%. The fio job is as follows: > > [global] > bs=4k > ioengine=libaio > iodepth=32 > direct=1 > sync=0 > time_based=1 > runtime=30 > clocksource=gettimeofday > ramp_time=5 > > [job1] > rw=randread > filename=/dev/vdb > size=4096M > write_bw_log=fio > write_iops_log=fio > write_lat_log=fio > log_avg_msec=1000 > > This benchmark was run on an raw image on LVM. The disk was an SSD > drive and -drive cache=none,aio=native was used. > > Tested-by: Pradeep Surisetty <psuriset@redhat.com> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > hw/block/virtio-blk.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c > index 6aefda4..a2137c8 100644 > --- a/hw/block/virtio-blk.c > +++ b/hw/block/virtio-blk.c > @@ -600,6 +600,8 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) > return; > } > > + blk_io_plug(s->blk); > + > while ((req = virtio_blk_get_request(s))) { > virtio_blk_handle_request(req, &mrb); > } > @@ -607,6 +609,8 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) > if (mrb.num_reqs) { > virtio_blk_submit_multireq(s->blk, &mrb); > } > + > + blk_io_unplug(s->blk); > } > > static void virtio_blk_dma_restart_bh(void *opaque) > -- > 2.4.3 > > Reviewed-by: Fam Zheng <famz@redhat.com>
On Mon, Jul 20, 2015 at 04:54:16PM +0100, Stefan Hajnoczi wrote: > The raw-posix block driver implements Linux AIO batching so multiple > requests can be submitted with a single io_submit(2) system call. > Batching is currently only used by virtio-scsi and > virtio-blk-data-plane. > > Enable batching for regular virtio-blk so the number of io_submit(2) > system calls is reduced for workloads with queue depth > 1. > > In 4KB random read performance tests with queue depth 32, the CPU > utilization on the host is reduced by 9.4%. The fio job is as follows: > > [global] > bs=4k > ioengine=libaio > iodepth=32 > direct=1 > sync=0 > time_based=1 > runtime=30 > clocksource=gettimeofday > ramp_time=5 > > [job1] > rw=randread > filename=/dev/vdb > size=4096M > write_bw_log=fio > write_iops_log=fio > write_lat_log=fio > log_avg_msec=1000 > > This benchmark was run on an raw image on LVM. The disk was an SSD > drive and -drive cache=none,aio=native was used. > > Tested-by: Pradeep Surisetty <psuriset@redhat.com> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > hw/block/virtio-blk.c | 4 ++++ > 1 file changed, 4 insertions(+) Thanks, applied to my master tree: https://github.com/stefanha/qemu/commits/master Stefan
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 6aefda4..a2137c8 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -600,6 +600,8 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) return; } + blk_io_plug(s->blk); + while ((req = virtio_blk_get_request(s))) { virtio_blk_handle_request(req, &mrb); } @@ -607,6 +609,8 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) if (mrb.num_reqs) { virtio_blk_submit_multireq(s->blk, &mrb); } + + blk_io_unplug(s->blk); } static void virtio_blk_dma_restart_bh(void *opaque)