From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36586) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1da12D-00020k-QN for qemu-devel@nongnu.org; Tue, 25 Jul 2017 10:42:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1da129-0000zQ-0X for qemu-devel@nongnu.org; Tue, 25 Jul 2017 10:42:05 -0400 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:53678 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 1da128-0000ye-NW for qemu-devel@nongnu.org; Tue, 25 Jul 2017 10:42:00 -0400 From: Peter Lieven Date: Tue, 25 Jul 2017 16:41:36 +0200 Message-Id: <1500993699-19299-8-git-send-email-pl@kamp.de> In-Reply-To: <1500993699-19299-1-git-send-email-pl@kamp.de> References: <1500993699-19299-1-git-send-email-pl@kamp.de> Subject: [Qemu-devel] [PATCH V5 07/10] block/qcow2: optimize qcow2_co_pwritev_compressed List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, kwolf@redhat.com, lersek@redhat.com, den@openvz.org, mreitz@redhat.com, eblake@redhat.com, berrange@redhat.com, Peter Lieven 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 ffe609d..a12b3d7 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -3428,7 +3428,7 @@ 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) { @@ -3438,8 +3438,8 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, return bdrv_truncate(bs->file, cluster_offset, PREALLOC_MODE_OFF, 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) { @@ -3448,8 +3448,10 @@ 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); @@ -3517,7 +3519,7 @@ 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; } -- 1.9.1