From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40954) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X1dq2-0004ZC-Nu for qemu-devel@nongnu.org; Mon, 30 Jun 2014 11:49:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X1dpw-0007TF-0a for qemu-devel@nongnu.org; Mon, 30 Jun 2014 11:49:50 -0400 Received: from mail-pd0-f170.google.com ([209.85.192.170]:36766) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X1dpv-0007Sz-Rt for qemu-devel@nongnu.org; Mon, 30 Jun 2014 11:49:43 -0400 Received: by mail-pd0-f170.google.com with SMTP id z10so8514720pdj.29 for ; Mon, 30 Jun 2014 08:49:42 -0700 (PDT) From: Ming Lei Date: Mon, 30 Jun 2014 23:47:40 +0800 Message-Id: <1404143260-9368-4-git-send-email-ming.lei@canonical.com> In-Reply-To: <1404143260-9368-1-git-send-email-ming.lei@canonical.com> References: <1404143260-9368-1-git-send-email-ming.lei@canonical.com> Subject: [Qemu-devel] [PATCH v1 3/3] dataplane: submit I/O at batch List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell , qemu-devel@nongnu.org, Paolo Bonzini , Stefan Hajnoczi Cc: Kevin Wolf , Ming Lei , Fam Zheng , "Michael S. Tsirkin" 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 --- 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 */ -- 1.7.9.5