From patchwork Tue Jun 27 12:34:08 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Lieven X-Patchwork-Id: 781192 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 3wxlkc4YVxz9s74 for ; Tue, 27 Jun 2017 22:35:20 +1000 (AEST) Received: from localhost ([::1]:52625 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dPpi9-0005Ai-Fm for incoming@patchwork.ozlabs.org; Tue, 27 Jun 2017 08:35:17 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42456) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dPphQ-00057Y-AJ for qemu-devel@nongnu.org; Tue, 27 Jun 2017 08:34:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dPphN-0005Gu-RV for qemu-devel@nongnu.org; Tue, 27 Jun 2017 08:34:32 -0400 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:45019 helo=mx01.kamp.de) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dPphN-0005F8-IB for qemu-devel@nongnu.org; Tue, 27 Jun 2017 08:34:29 -0400 Received: (qmail 22681 invoked by uid 89); 27 Jun 2017 12:34:24 -0000 Received: from [195.62.97.28] by client-16-kamp (envelope-from , uid 89) with qmail-scanner-2010/03/19-MF (clamdscan: 0.99.2/23511. avast: 1.2.2/17010300. spamassassin: 3.4.1. Clear:RC:1(195.62.97.28):. Processed in 0.241906 secs); 27 Jun 2017 12:34:24 -0000 Received: from smtp.kamp.de (HELO submission.kamp.de) ([195.62.97.28]) by mx01.kamp.de with ESMTPS (DHE-RSA-AES256-GCM-SHA384 encrypted); 27 Jun 2017 12:34:21 -0000 X-GL_Whitelist: yes Received: (qmail 29616 invoked from network); 27 Jun 2017 12:34:20 -0000 Received: from lieven-pc.kamp-intra.net (HELO lieven-pc) (relay@kamp.de@::ffff:172.21.12.60) by submission.kamp.de with ESMTPS (DHE-RSA-AES256-GCM-SHA384 encrypted) ESMTPA; 27 Jun 2017 12:34:20 -0000 Received: by lieven-pc (Postfix, from userid 1000) id 7FE4E26C5D; Tue, 27 Jun 2017 14:34:20 +0200 (CEST) From: Peter Lieven To: qemu-block@nongnu.org Date: Tue, 27 Jun 2017 14:34:08 +0200 Message-Id: <1498566850-7934-3-git-send-email-pl@kamp.de> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1498566850-7934-1-git-send-email-pl@kamp.de> References: <1498566850-7934-1-git-send-email-pl@kamp.de> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2a02:248:0:51::16 Subject: [Qemu-devel] [PATCH 2/4] block/qcow2: optimize qcow2_co_pwritev_compressed 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: kwolf@redhat.com, Peter Lieven , qemu-devel@nongnu.org, mreitz@redhat.com, den@openvz.org, lersek@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" if we specify exactly one iov of s->cluster_size bytes we can avoid the bounce buffer. Signed-off-by: Peter Lieven --- block/qcow2.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 893b145..c91eb1f 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2716,7 +2716,7 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, struct iovec iov; z_stream strm; int ret, out_len; - uint8_t *buf, *out_buf; + uint8_t *buf, *out_buf, *local_buf = NULL; uint64_t cluster_offset; if (bytes == 0) { @@ -2726,8 +2726,8 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, return bdrv_truncate(bs->file, cluster_offset, NULL); } - buf = qemu_blockalign(bs, s->cluster_size); - if (bytes != s->cluster_size) { + if (bytes != s->cluster_size || qiov->niov != 1) { + buf = local_buf = qemu_blockalign(bs, s->cluster_size); if (bytes > s->cluster_size || offset + bytes != bs->total_sectors << BDRV_SECTOR_BITS) { @@ -2736,8 +2736,10 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, } /* Zero-pad last write if image size is not cluster aligned */ memset(buf + bytes, 0, s->cluster_size - bytes); + qemu_iovec_to_buf(qiov, 0, buf, bytes); + } else { + buf = qiov->iov[0].iov_base; } - qemu_iovec_to_buf(qiov, 0, buf, bytes); out_buf = g_malloc(s->cluster_size); @@ -2805,7 +2807,7 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, success: ret = 0; fail: - qemu_vfree(buf); + qemu_vfree(local_buf); g_free(out_buf); return ret; }