From patchwork Mon Nov 24 14:29:38 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 413749 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 93179140168 for ; Tue, 25 Nov 2014 01:32:17 +1100 (AEDT) Received: from localhost ([::1]:52950 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XsugZ-0000JW-95 for incoming@patchwork.ozlabs.org; Mon, 24 Nov 2014 09:32:15 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55643) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xsueh-0006Kw-EP for qemu-devel@nongnu.org; Mon, 24 Nov 2014 09:30:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xsueb-0000N0-D1 for qemu-devel@nongnu.org; Mon, 24 Nov 2014 09:30:19 -0500 Received: from mail-pa0-f42.google.com ([209.85.220.42]:58783) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xsueb-0000Mn-8I for qemu-devel@nongnu.org; Mon, 24 Nov 2014 09:30:13 -0500 Received: by mail-pa0-f42.google.com with SMTP id et14so9592340pad.15 for ; Mon, 24 Nov 2014 06:30:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=7NS+1o2RcMyYhfFDFBrzTQ5xv20A1xBJ/fYeTbzJZz0=; b=k+VP/eZ/OphRXlb2oVP4Ib1l4Iy6nc+z3zGaWi/1ktRXnKxTu7I350NMBv4riRO9tb 75yZTFdpkIa4OqfLN/xb5evjAnEzZ3xWezAbl1+KerzyusViTK0LK32mPhXapaj+Dzmu rhWYJ71fIbzHk/JJSZ7f8eqICdnlIr6koMx3X6xi7uVN/BREd+D1VwzfmoeLhvvx8cmk D56t3A84+AlLdZveG2j3rlGDvR/FfcRhCJuaXFfTYrqyXJ9NH6cT4UBOGUArlJAuBoI2 bZcoOAV/8ckAVKppLmo05rC5d/b6uMMEM7mR7Il2Utrz/mPfBjlqe8u6TIfJvveDsIFv Dbig== X-Received: by 10.68.165.100 with SMTP id yx4mr33340101pbb.79.1416839412563; Mon, 24 Nov 2014 06:30:12 -0800 (PST) Received: from localhost ([116.24.103.233]) by mx.google.com with ESMTPSA id xn4sm12726788pab.9.2014.11.24.06.30.11 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Mon, 24 Nov 2014 06:30:11 -0800 (PST) From: Ming Lei To: qemu-devel@nongnu.org, Paolo Bonzini , Stefan Hajnoczi , Kevin Wolf Date: Mon, 24 Nov 2014 22:29:38 +0800 Message-Id: <1416839379-19677-3-git-send-email-ming.lei@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1416839379-19677-1-git-send-email-ming.lei@canonical.com> References: <1416839379-19677-1-git-send-email-ming.lei@canonical.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.220.42 Cc: Ming Lei Subject: [Qemu-devel] [PATCH v5 2/3] linux-aio: handling -EAGAIN for !s->io_q.plugged case X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Previously -EAGAIN is simply ignored for !s->io_q.plugged case, and sometimes it is easy to cause -EIO to VM, such as NVME device. This patch handles -EAGAIN by io queue for !s->io_q.plugged case, and it will be retried in following aio completion cb. Suggested-by: Paolo Bonzini Signed-off-by: Ming Lei --- block/linux-aio.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-) diff --git a/block/linux-aio.c b/block/linux-aio.c index 70312a4..0cb098d 100644 --- a/block/linux-aio.c +++ b/block/linux-aio.c @@ -282,12 +282,17 @@ static int ioq_enqueue(struct qemu_laio_state *s, struct iocb *iocb) s->io_q.iocbs[idx++] = iocb; s->io_q.idx = idx; - /* submit immediately if queue depth is above 2/3 */ - if (idx > s->io_q.size * 2 / 3) { - return ioq_submit(s); + /* + * This is reached in two cases: queue not plugged but io_submit + * returned -EAGAIN, or queue plugged. In the latter case, start + * submitting some I/O if the queue is getting too full. In the + * former case, instead, wait until an I/O operation is completed. + */ + if (!s->io_q.plugged || likely(idx < s->io_q.size * 2 / 3)) { + return 0; } - return 0; + return ioq_submit(s); } void laio_io_plug(BlockDriverState *bs, void *aio_ctx) @@ -348,15 +353,18 @@ BlockAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd, } io_set_eventfd(&laiocb->iocb, event_notifier_get_fd(&s->e)); - if (!s->io_q.plugged) { - if (io_submit(s->ctx, 1, &iocbs) < 0) { - goto out_free_aiocb; - } - } else { - if (ioq_enqueue(s, iocbs) < 0) { + /* Switch to queue mode until -EAGAIN is handled */ + if (!s->io_q.plugged && !s->io_q.idx) { + int ret = io_submit(s->ctx, 1, &iocbs); + if (ret >= 0) { + return &laiocb->common; + } else if (ret != -EAGAIN) { goto out_free_aiocb; } } + if (ioq_enqueue(s, iocbs) < 0) { + goto out_free_aiocb; + } return &laiocb->common; out_free_aiocb: