| Message ID | 1404143260-9368-4-git-send-email-ming.lei@canonical.com |
|---|---|
| State | New |
| Headers | show |
Il 30/06/2014 17:47, Ming Lei ha scritto: > Before commit 580b6b2aa2(dataplane: use the Qemu block > layer for I/O), dataplane for virtio-blk submits block > I/O at batch. > > This commit 580b6b2aa2 replaces the custom linux AIO > implementation(including I/O batch) with Qemu block > layer, but this commit causes ~40% throughput regression > on virtio-blk performance, and removing submitting I/O > at batch is one of the cause. > > This patch applys the new introduced bdrv_io_plug() and > bdrv_io_unplug() interfaces to support submitting I/O > at batch for Qemu block layer, and in my test, the change > can improve thoughput by ~30% with 'aio=native'. > > Following my fio test script: > > [global] > direct=1 > size=4G > bsrange=4k-4k > timeout=40 > numjobs=4 > ioengine=libaio > iodepth=64 > filename=/dev/vdc > group_reporting=1 > > [f] > rw=randread > > Result on one of my small machine(host: x86_64, 2cores, 4thread, guest: 4cores): > - qemu master: 59K IOPS > - qemu master with these patches: 81K IOPS > - 2.0.0 release(dataplane using custom linux aio): 104K IOPS > > Signed-off-by: Ming Lei <ming.lei@canonical.com> > --- > hw/block/dataplane/virtio-blk.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c > index c10b7b7..8fefcce 100644 > --- a/hw/block/dataplane/virtio-blk.c > +++ b/hw/block/dataplane/virtio-blk.c > @@ -289,6 +289,7 @@ static void handle_notify(EventNotifier *e) > int ret; > > event_notifier_test_and_clear(&s->host_notifier); > + bdrv_io_plug(s->blk->conf.bs); > for (;;) { > /* Disable guest->host notifies to avoid unnecessary vmexits */ > vring_disable_notification(s->vdev, &s->vring); > @@ -322,6 +323,7 @@ static void handle_notify(EventNotifier *e) > break; > } > } > + bdrv_io_unplug(s->blk->conf.bs); > } > > /* Context: QEMU global mutex held */ > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> but please add it to the non-dataplane path as well, and to virtio-scsi. Paolo
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index c10b7b7..8fefcce 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -289,6 +289,7 @@ static void handle_notify(EventNotifier *e) int ret; event_notifier_test_and_clear(&s->host_notifier); + bdrv_io_plug(s->blk->conf.bs); for (;;) { /* Disable guest->host notifies to avoid unnecessary vmexits */ vring_disable_notification(s->vdev, &s->vring); @@ -322,6 +323,7 @@ static void handle_notify(EventNotifier *e) break; } } + bdrv_io_unplug(s->blk->conf.bs); } /* Context: QEMU global mutex held */
Before commit 580b6b2aa2(dataplane: use the Qemu block layer for I/O), dataplane for virtio-blk submits block I/O at batch. This commit 580b6b2aa2 replaces the custom linux AIO implementation(including I/O batch) with Qemu block layer, but this commit causes ~40% throughput regression on virtio-blk performance, and removing submitting I/O at batch is one of the cause. This patch applys the new introduced bdrv_io_plug() and bdrv_io_unplug() interfaces to support submitting I/O at batch for Qemu block layer, and in my test, the change can improve thoughput by ~30% with 'aio=native'. Following my fio test script: [global] direct=1 size=4G bsrange=4k-4k timeout=40 numjobs=4 ioengine=libaio iodepth=64 filename=/dev/vdc group_reporting=1 [f] rw=randread Result on one of my small machine(host: x86_64, 2cores, 4thread, guest: 4cores): - qemu master: 59K IOPS - qemu master with these patches: 81K IOPS - 2.0.0 release(dataplane using custom linux aio): 104K IOPS Signed-off-by: Ming Lei <ming.lei@canonical.com> --- hw/block/dataplane/virtio-blk.c | 2 ++ 1 file changed, 2 insertions(+)