From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38363) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1co63t-0007Cr-AC for qemu-devel@nongnu.org; Wed, 15 Mar 2017 06:21:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1co63s-0005f6-Ea for qemu-devel@nongnu.org; Wed, 15 Mar 2017 06:21:45 -0400 Date: Wed, 15 Mar 2017 11:21:36 +0100 From: Kevin Wolf Message-ID: <20170315102136.GD4030@noname.str.redhat.com> References: <1489549053-31728-1-git-send-email-jemmy858585@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1489549053-31728-1-git-send-email-jemmy858585@gmail.com> Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v2] migration/block: Avoid invoking blk_drain too frequently List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Lidong Chen Cc: qemu-devel@nongnu.org, famz@redhat.com, qemu-block@nongnu.org, quintela@redhat.com, dgilbert@redhat.com, stefanha@redhat.com Am 15.03.2017 um 04:37 hat Lidong Chen geschrieben: > Increase bmds->cur_dirty after submit io, so reduce the frequency > involve into blk_drain, and improve the performance obviously > when block migration. > > The performance test result of this patch: > > During the block dirty save phase, this patch improve guest os IOPS > from 4.0K to 9.5K. and improve the migration speed from > 505856 rsec/s to 855756 rsec/s. > > Signed-off-by: Lidong Chen > --- > migration/block.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/migration/block.c b/migration/block.c > index 6741228..7734ff7 100644 > --- a/migration/block.c > +++ b/migration/block.c > @@ -576,6 +576,9 @@ static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds, > } > > bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, sector, nr_sectors); > + sector += nr_sectors; sector += BDRV_SECTORS_PER_DIRTY_CHUNK would be acceptable here... > + bmds->cur_dirty = sector; > + > break; > } > sector += BDRV_SECTORS_PER_DIRTY_CHUNK; > bmds->cur_dirty = sector; > } ...which would make it the same code as the rest of the loop. It could be nicer to reuse the same code and just set a bool when a request is submitted so that the loop terminates after that. But that's just a matter of taste, so I'll still give: Reviewed-by: Kevin Wolf