From patchwork Thu Aug 29 14:00:02 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 270831 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 72F662C00B1 for ; Fri, 30 Aug 2013 00:01:32 +1000 (EST) Received: from localhost ([::1]:43542 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VF2mw-0006dH-AK for incoming@patchwork.ozlabs.org; Thu, 29 Aug 2013 10:01:30 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53843) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VF2mD-0006Xs-OU for qemu-devel@nongnu.org; Thu, 29 Aug 2013 10:00:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VF2m5-00083D-15 for qemu-devel@nongnu.org; Thu, 29 Aug 2013 10:00:45 -0400 Received: from mail-ea0-x236.google.com ([2a00:1450:4013:c01::236]:51594) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VF2m4-000830-PZ for qemu-devel@nongnu.org; Thu, 29 Aug 2013 10:00:36 -0400 Received: by mail-ea0-f182.google.com with SMTP id o10so269469eaj.27 for ; Thu, 29 Aug 2013 07:00:35 -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:in-reply-to:references; bh=igZUiDmuokZnzrSWjIGD36sXflqKoFTRU49uHzxDf0w=; b=Kk36BX+0jEZhr5xIrBh5UmshGcgunFY/ocgSGBMn6GNITKENjodX89MAqE8AMXZBEl KL6ORM9Jkws8HvUN2xIKlApV576Y7Pzp3RzpZyqBpsA0T3UxioI0LxBTCxZyFUE+26P8 oHMKSfOTwY3cG7xohV2hSkW49jYqDXwAo9NFJpcxkLqoDLC7NlvG+VbJNfmHffEkYP5D z28ghWCDBLMgrx9ZbTMFjIknRpUPiDgePjKpbhcFkX5H5F1qXI5dQqgYpOHR9eZL9Ac3 P9o90RLykB8x+lAfedEtktwwL5eyhN/axf2jnlOGOSgj6zL6POaeTuudYqHO9fk+cLoH p9Hw== X-Received: by 10.14.223.134 with SMTP id v6mr45905eep.88.1377784835891; Thu, 29 Aug 2013 07:00:35 -0700 (PDT) Received: from yakj.usersys.redhat.com (nat-pool-mxp-t.redhat.com. [209.132.186.18]) by mx.google.com with ESMTPSA id p5sm46359028eeg.5.1969.12.31.16.00.00 (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Thu, 29 Aug 2013 07:00:34 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Thu, 29 Aug 2013 16:00:02 +0200 Message-Id: <1377784821-29561-3-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1377784821-29561-1-git-send-email-pbonzini@redhat.com> References: <1377784821-29561-1-git-send-email-pbonzini@redhat.com> X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2a00:1450:4013:c01::236 Cc: kwolf@redhat.com, stefanha@redhat.com Subject: [Qemu-devel] [PATCH v4 02/21] 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. Reviewed-by: Eric Blake Signed-off-by: Paolo Bonzini --- block/cow.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/block/cow.c b/block/cow.c index fa3d41f..9ae2d6a 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; }