From patchwork Tue Oct 31 18:59:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 13442209 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E2176C4332F for ; Tue, 31 Oct 2023 19:04:06 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qxtyV-0004OC-42; Tue, 31 Oct 2023 15:00:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qxty8-0004CX-Rr for qemu-devel@nongnu.org; Tue, 31 Oct 2023 15:00:06 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qxtxh-000684-Mt for qemu-devel@nongnu.org; Tue, 31 Oct 2023 15:00:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1698778777; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=csEwfXNoo9FaZsxDRm4Xw2984Qo8bNTHeVvdleYTDNU=; b=F9JpQ1Dyt/lyGjPopTFfzdn/5lh/OVtqM7USUgsn5yWeudHL1hDe0PTwptg/yg5IMeCELe Ra9PCD8jmoBFmGk2lYgDVfK/vXllo6lUkZHNSzEa/r4QV8v+fejxm8goXiLANW4MzNJZy2 130TjE2Pk/DYctr7gng1+uc4C3Bbg4c= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-318-1DncB-NlM7GVdevAUDlTHw-1; Tue, 31 Oct 2023 14:59:34 -0400 X-MC-Unique: 1DncB-NlM7GVdevAUDlTHw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7903F8678A3; Tue, 31 Oct 2023 18:59:34 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.39.194.218]) by smtp.corp.redhat.com (Postfix) with ESMTP id DDD1E25C0; Tue, 31 Oct 2023 18:59:33 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 17/27] virtio-blk: remove batch notification BH Date: Tue, 31 Oct 2023 19:59:08 +0100 Message-ID: <20231031185918.346940-18-kwolf@redhat.com> In-Reply-To: <20231031185918.346940-1-kwolf@redhat.com> References: <20231031185918.346940-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.481, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Stefan Hajnoczi There is a batching mechanism for virtio-blk Used Buffer Notifications that is no longer needed because the previous commit added batching to virtio_notify_irqfd(). Note that this mechanism was rarely used in practice because it is only enabled when EVENT_IDX is not negotiated by the driver. Modern drivers enable EVENT_IDX. Reviewed-by: Eric Blake Signed-off-by: Stefan Hajnoczi Message-ID: <20230913200045.1024233-5-stefanha@redhat.com> Reviewed-by: Michael S. Tsirkin Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- hw/block/dataplane/virtio-blk.c | 48 +-------------------------------- 1 file changed, 1 insertion(+), 47 deletions(-) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index da36fcfd0b..f83bb0f116 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -31,9 +31,6 @@ struct VirtIOBlockDataPlane { VirtIOBlkConf *conf; VirtIODevice *vdev; - QEMUBH *bh; /* bh for guest notification */ - unsigned long *batch_notify_vqs; - bool batch_notifications; /* Note that these EventNotifiers are assigned by value. This is * fine as long as you do not call event_notifier_cleanup on them @@ -47,36 +44,7 @@ struct VirtIOBlockDataPlane { /* Raise an interrupt to signal guest, if necessary */ void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq) { - if (s->batch_notifications) { - set_bit(virtio_get_queue_index(vq), s->batch_notify_vqs); - qemu_bh_schedule(s->bh); - } else { - virtio_notify_irqfd(s->vdev, vq); - } -} - -static void notify_guest_bh(void *opaque) -{ - VirtIOBlockDataPlane *s = opaque; - unsigned nvqs = s->conf->num_queues; - unsigned long bitmap[BITS_TO_LONGS(nvqs)]; - unsigned j; - - memcpy(bitmap, s->batch_notify_vqs, sizeof(bitmap)); - memset(s->batch_notify_vqs, 0, sizeof(bitmap)); - - for (j = 0; j < nvqs; j += BITS_PER_LONG) { - unsigned long bits = bitmap[j / BITS_PER_LONG]; - - while (bits != 0) { - unsigned i = j + ctzl(bits); - VirtQueue *vq = virtio_get_queue(s->vdev, i); - - virtio_notify_irqfd(s->vdev, vq); - - bits &= bits - 1; /* clear right-most bit */ - } - } + virtio_notify_irqfd(s->vdev, vq); } /* Context: QEMU global mutex held */ @@ -126,9 +94,6 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf, } else { s->ctx = qemu_get_aio_context(); } - s->bh = aio_bh_new_guarded(s->ctx, notify_guest_bh, s, - &DEVICE(vdev)->mem_reentrancy_guard); - s->batch_notify_vqs = bitmap_new(conf->num_queues); *dataplane = s; @@ -146,8 +111,6 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s) vblk = 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)); } @@ -173,12 +136,6 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev) s->starting = true; - if (!virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) { - s->batch_notifications = true; - } else { - s->batch_notifications = false; - } - /* Set up guest notifier (irq) */ r = k->set_guest_notifiers(qbus->parent, nvqs, true); if (r != 0) { @@ -370,9 +327,6 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev) aio_context_release(s->ctx); - qemu_bh_cancel(s->bh); - notify_guest_bh(s); /* final chance to notify guest */ - /* Clean up guest notifier (irq) */ k->set_guest_notifiers(qbus->parent, nvqs, false);