From nobody Sat May 4 02:17:30 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1513690567797988.4763334909325; Tue, 19 Dec 2017 05:36:07 -0800 (PST) Received: from localhost ([::1]:44736 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eRI3t-00076X-B8 for importer@patchew.org; Tue, 19 Dec 2017 08:36:01 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49094) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eRI1l-0005gs-Fj for qemu-devel@nongnu.org; Tue, 19 Dec 2017 08:33:50 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eRI1k-0003EK-HV for qemu-devel@nongnu.org; Tue, 19 Dec 2017 08:33:49 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:2055 helo=huawei.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eRI1g-00039l-9q; Tue, 19 Dec 2017 08:33:44 -0500 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 2A7E3B7177976; Tue, 19 Dec 2017 21:33:27 +0800 (CST) Received: from localhost.localdomain (10.175.104.228) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.361.1; Tue, 19 Dec 2017 21:33:23 +0800 From: sochin.jiang To: , , Date: Tue, 19 Dec 2017 21:33:03 +0800 Message-ID: <1513690383-27269-1-git-send-email-sochin.jiang@huawei.com> X-Mailer: git-send-email 1.8.3.1 MIME-Version: 1.0 X-Originating-IP: [10.175.104.228] X-CFilter-Loop: Reflected X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 45.249.212.191 Subject: [Qemu-devel] [PATCH] virtio-blk: notify guest directly X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: sochin.jiang@huawei.com, qemu-devel@nongnu.org, qemu-block@nongnu.org, eric.fangyi@huawei.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "sochin.jiang" Till now, we've already notify guest as a batch mostly, an extra BH won't decrease guest interrupts much, but cause a significant notification loss. Generally, we could have 15% or so performance lost in single queue IO models, as I tested. Signed-off-by: sochin.jiang --- hw/block/dataplane/virtio-blk.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-bl= k.c index 5556f0e..a261a1d 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -32,7 +32,6 @@ struct VirtIOBlockDataPlane { =20 VirtIOBlkConf *conf; VirtIODevice *vdev; - QEMUBH *bh; /* bh for guest notification */ unsigned long *batch_notify_vqs; =20 /* Note that these EventNotifiers are assigned by value. This is @@ -44,14 +43,7 @@ struct VirtIOBlockDataPlane { AioContext *ctx; }; =20 -/* Raise an interrupt to signal guest, if necessary */ -void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq) -{ - set_bit(virtio_get_queue_index(vq), s->batch_notify_vqs); - qemu_bh_schedule(s->bh); -} - -static void notify_guest_bh(void *opaque) +static void notify_guest(void *opaque) { VirtIOBlockDataPlane *s =3D opaque; unsigned nvqs =3D s->conf->num_queues; @@ -75,7 +67,12 @@ static void notify_guest_bh(void *opaque) } } =20 -/* Context: QEMU global mutex held */ +/* Raise an interrupt to signal guest, if necessary */ +void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq) +{ + set_bit(virtio_get_queue_index(vq), s->batch_notify_vqs); + notify_guest(s); +} void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf, VirtIOBlockDataPlane **dataplane, Error **errp) @@ -122,7 +119,6 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, V= irtIOBlkConf *conf, } else { s->ctx =3D qemu_get_aio_context(); } - s->bh =3D aio_bh_new(s->ctx, notify_guest_bh, s); s->batch_notify_vqs =3D bitmap_new(conf->num_queues); =20 *dataplane =3D s; @@ -140,7 +136,6 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane= *s) vblk =3D VIRTIO_BLK(s->vdev); assert(!vblk->dataplane_started); g_free(s->batch_notify_vqs); - qemu_bh_delete(s->bh); if (s->iothread) { object_unref(OBJECT(s->iothread)); } --=20 1.8.3.1