From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56199) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y5thT-0005Hq-Bv for qemu-devel@nongnu.org; Tue, 30 Dec 2014 05:06:52 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Y5thS-0003ZJ-Iw for qemu-devel@nongnu.org; Tue, 30 Dec 2014 05:06:51 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:35436 helo=relay.sw.ru) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y5thS-0003Ys-7r for qemu-devel@nongnu.org; Tue, 30 Dec 2014 05:06:50 -0500 From: "Denis V. Lunev" Date: Tue, 30 Dec 2014 13:07:09 +0300 Message-Id: <1419934032-24216-7-git-send-email-den@openvz.org> In-Reply-To: <1419934032-24216-1-git-send-email-den@openvz.org> References: <1419931701-19362-1-git-send-email-den@openvz.org> <1419934032-24216-1-git-send-email-den@openvz.org> Subject: [Qemu-devel] [PATCH 16/19] block/parallels: no need to flush on each block allocation table update List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , "Denis V. Lunev" , qemu-devel@nongnu.org, Stefan Hajnoczi >>From the point of guest each write to real disk prior to disk barrier operation could be lost. Therefore there is no problem that "not synced" new block is lost due to not updated allocation table if QEMU is crashed. This patch improves writing performance of qemu-img create -f parallels -o cluster_size=64k ./1.hds 64G qemu-io -f parallels -c "write -P 0x11 0 1024k" 1.hds from 45 Mb/sec to 160 Mb/sec on my SSD disk. The gain on rotational media is much more sufficient, from 800 Kb/sec to 45 Mb/sec. Signed-off-by: Denis V. Lunev CC: Kevin Wolf CC: Stefan Hajnoczi --- block/parallels.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/parallels.c b/block/parallels.c index ddc3aee..46cf031 100644 --- a/block/parallels.c +++ b/block/parallels.c @@ -194,7 +194,7 @@ static int64_t allocate_sector(BlockDriverState *bs, int64_t sector_num) tmp = cpu_to_le32(s->bat[idx]); - ret = bdrv_pwrite_sync(bs->file, bat_offset(idx), &tmp, sizeof(tmp)); + ret = bdrv_pwrite(bs->file, bat_offset(idx), &tmp, sizeof(tmp)); if (ret < 0) { return ret; } -- 1.9.1