From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56966) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1coKHv-0005Ez-T0 for qemu-devel@nongnu.org; Wed, 15 Mar 2017 21:33:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1coKHv-0000iG-17 for qemu-devel@nongnu.org; Wed, 15 Mar 2017 21:33:11 -0400 Date: Thu, 16 Mar 2017 09:33:01 +0800 From: Fam Zheng Message-ID: <20170316013301.GB21865@lemon.lan> References: <1489549053-31728-1-git-send-email-jemmy858585@gmail.com> <20170315111021.GD3088@lemon.lan> <20170315173108.GB2701@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170315173108.GB2701@work-vm> Subject: Re: [Qemu-devel] [PATCH v2] migration/block: Avoid invoking blk_drain too frequently List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: Lidong Chen , qemu-devel@nongnu.org, stefanha@redhat.com, quintela@redhat.com, qemu-block@nongnu.org On Wed, 03/15 17:31, Dr. David Alan Gilbert wrote: > * Fam Zheng (famz@redhat.com) wrote: > > On Wed, 03/15 11:37, Lidong Chen wrote: > > > 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; > > > + bmds->cur_dirty = sector; > > > + > > > break; > > > } > > > sector += BDRV_SECTORS_PER_DIRTY_CHUNK; > > > -- > > > 1.8.3.1 > > > > > > > Nice catch above all, thank you! > > > > Reviewed-by: Fam Zheng > > Are you taking that via a block pull? I can do that, but I'm not sure whether it should go to 2.9. This is a performance improvement, which usually doesn't qualify as bug fixes. But this also looks like a mistake in original code. Fam