From patchwork Tue Jul 16 16:29:13 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 259452 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)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id D62A22C0177 for ; Wed, 17 Jul 2013 02:32:20 +1000 (EST) Received: from localhost ([::1]:40405 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uz8Ak-0004AE-M8 for incoming@patchwork.ozlabs.org; Tue, 16 Jul 2013 12:32:18 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50468) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uz88Q-000182-ND for qemu-devel@nongnu.org; Tue, 16 Jul 2013 12:29:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uz88O-0005Gl-Oo for qemu-devel@nongnu.org; Tue, 16 Jul 2013 12:29:54 -0400 Received: from mail-qa0-x229.google.com ([2607:f8b0:400d:c00::229]:36045) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uz88O-0005Gh-J0 for qemu-devel@nongnu.org; Tue, 16 Jul 2013 12:29:52 -0400 Received: by mail-qa0-f41.google.com with SMTP id f14so2391734qak.7 for ; Tue, 16 Jul 2013 09:29:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:x-mailer:in-reply-to :references; bh=fmwebIlk1JGq6xyGosHz622eRBIhJ6rT9qxhi5x6294=; b=JABV/TwmqHrMfrXf9w0i2VAH9uxPz512+4BLsb0AsLzKOTPkT4Xv9mj+IWettU0SOd adrTMmX6cR043xw1K84df/Yt0l0AWirqmLB1q97TAkO1rEJvf5DMxHwW0yEN/da1lReI 30WRbCqaxbk8g2FMzX8sEAgWibj8Go4ue3cWPXKqtDwKFNCjNl4FIim1J/PGYWoXoFri yUWZt92564pXBz7siJGCyVLpKAkC62gq/k1p9O5KO/bZE0gc2C3zBcliVXQyyh2hauG5 6GJ7tWAYuI/fE3wcYZ/kEhtctR3k1FvYBnxIX+d2l5mHCC2lz+pRkCYHglruSB6RLSKP rDBA== X-Received: by 10.224.128.2 with SMTP id i2mr4433470qas.11.1373992192241; Tue, 16 Jul 2013 09:29:52 -0700 (PDT) Received: from yakj.usersys.redhat.com (net-2-39-8-162.cust.dsl.vodafone.it. [2.39.8.162]) by mx.google.com with ESMTPSA id l2sm2785730qez.2.2013.07.16.09.29.50 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Tue, 16 Jul 2013 09:29:51 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Tue, 16 Jul 2013 18:29:13 +0200 Message-Id: <1373992168-26043-3-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1373992168-26043-1-git-send-email-pbonzini@redhat.com> References: <1373992168-26043-1-git-send-email-pbonzini@redhat.com> X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2607:f8b0:400d:c00::229 Cc: pl@kamp.de, famz@redhat.com, stefanha@redhat.com Subject: [Qemu-devel] [PATCH v2 02/17] cow: make writes go at a less indecent speed 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 Only sync once per write, rather than once per sector. Signed-off-by: Paolo Bonzini Reviewed-by: Eric Blake --- block/cow.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/block/cow.c b/block/cow.c index fa3d41f..304e4c7 100644 --- a/block/cow.c +++ b/block/cow.c @@ -106,7 +106,7 @@ static int cow_open(BlockDriverState *bs, QDict *options, int flags) * XXX(hch): right now these functions are extremely inefficient. * We should just read the whole bitmap we'll need in one go instead. */ -static inline int cow_set_bit(BlockDriverState *bs, int64_t bitnum) +static inline int cow_set_bit(BlockDriverState *bs, int64_t bitnum, bool *first) { uint64_t offset = sizeof(struct cow_header_v2) + bitnum / 8; uint8_t bitmap; @@ -117,9 +117,21 @@ static inline int cow_set_bit(BlockDriverState *bs, int64_t bitnum) return ret; } + if (bitmap & (1 << (bitnum % 8))) { + return 0; + } + + if (*first) { + ret = bdrv_flush(bs->file); + if (ret < 0) { + return ret; + } + *first = false; + } + bitmap |= (1 << (bitnum % 8)); - ret = bdrv_pwrite_sync(bs->file, offset, &bitmap, sizeof(bitmap)); + ret = bdrv_pwrite(bs->file, offset, &bitmap, sizeof(bitmap)); if (ret < 0) { return ret; } @@ -181,9 +193,10 @@ static int cow_update_bitmap(BlockDriverState *bs, int64_t sector_num, { int error = 0; int i; + bool first = true; for (i = 0; i < nb_sectors; i++) { - error = cow_set_bit(bs, sector_num + i); + error = cow_set_bit(bs, sector_num + i, &first); if (error) { break; }