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Processed in 0.342327 secs); 29 Jun 2017 10:57:33 -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); 29 Jun 2017 10:57:30 -0000 X-GL_Whitelist: yes Received: (qmail 12784 invoked from network); 29 Jun 2017 10:57:15 -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; 29 Jun 2017 10:57:15 -0000 Received: by lieven-pc (Postfix, from userid 1000) id ACDF426C60; Thu, 29 Jun 2017 12:57:15 +0200 (CEST) From: Peter Lieven To: qemu-block@nongnu.org Date: Thu, 29 Jun 2017 12:57:09 +0200 Message-Id: <1498733831-15254-7-git-send-email-pl@kamp.de> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1498733831-15254-1-git-send-email-pl@kamp.de> References: <1498733831-15254-1-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 V2 6/8] 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+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP 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 39a8afc..0a7202a 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2750,7 +2750,7 @@ 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) { @@ -2760,8 +2760,8 @@ 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) { @@ -2770,8 +2770,10 @@ 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); @@ -2839,7 +2841,7 @@ 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; }