From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57023) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YxtBZ-0000sm-Id for qemu-devel@nongnu.org; Thu, 28 May 2015 04:29:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YxtBY-00061N-HZ for qemu-devel@nongnu.org; Thu, 28 May 2015 04:29:05 -0400 Message-ID: <5566D1C5.2080704@redhat.com> Date: Thu, 28 May 2015 10:28:53 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1432790990-25383-1-git-send-email-famz@redhat.com> <1432790990-25383-4-git-send-email-famz@redhat.com> In-Reply-To: <1432790990-25383-4-git-send-email-famz@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v6 3/8] mirror: Do zero write on target if sectors not allocated List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng , qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Jeff Cody , qemu-stable@nongnu.org, Stefan Hajnoczi , jsnow@redhat.com, wangxiaolong@ucloud.cn On 28/05/2015 07:29, Fam Zheng wrote: > If guest discards a source cluster, mirroring with bdrv_aio_readv is overkill. > Some protocols do zero upon discard, where it's best to use > bdrv_aio_write_zeroes, otherwise, bdrv_aio_discard will be enough. > > Signed-off-by: Fam Zheng Reviewed-by: Paolo Bonzini > --- > block/mirror.c | 20 ++++++++++++++++++-- > 1 file changed, 18 insertions(+), 2 deletions(-) > > diff --git a/block/mirror.c b/block/mirror.c > index 85995b2..ba33254 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -164,6 +164,8 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) > int64_t end, sector_num, next_chunk, next_sector, hbitmap_next_sector; > uint64_t delay_ns = 0; > MirrorOp *op; > + int pnum; > + int64_t ret; > > s->sector_num = hbitmap_iter_next(&s->hbi); > if (s->sector_num < 0) { > @@ -290,8 +292,22 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) > s->in_flight++; > s->sectors_in_flight += nb_sectors; > trace_mirror_one_iteration(s, sector_num, nb_sectors); > - bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors, > - mirror_read_complete, op); > + > + ret = bdrv_get_block_status_above(source, NULL, sector_num, > + nb_sectors, &pnum); > + if (ret < 0 || pnum < nb_sectors || > + (ret & BDRV_BLOCK_DATA && !(ret & BDRV_BLOCK_ZERO))) { > + bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors, > + mirror_read_complete, op); > + } else if (ret & BDRV_BLOCK_ZERO) { > + bdrv_aio_write_zeroes(s->target, sector_num, op->nb_sectors, > + s->unmap ? BDRV_REQ_MAY_UNMAP : 0, > + mirror_write_complete, op); > + } else { > + assert(!(ret & BDRV_BLOCK_DATA)); > + bdrv_aio_discard(s->target, sector_num, op->nb_sectors, > + mirror_write_complete, op); > + } > return delay_ns; > } > >