From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43924) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bPAbI-00084t-3k for qemu-devel@nongnu.org; Mon, 18 Jul 2016 11:36:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bPAbD-0006ny-5i for qemu-devel@nongnu.org; Mon, 18 Jul 2016 11:36:56 -0400 References: <1468516741-82174-1-git-send-email-vsementsov@virtuozzo.com> From: "Denis V. Lunev" Message-ID: <578CF78B.8050909@openvz.org> Date: Mon, 18 Jul 2016 18:36:43 +0300 MIME-Version: 1.0 In-Reply-To: <1468516741-82174-1-git-send-email-vsementsov@virtuozzo.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2] mirror: double performance of the bulk stage if the disc is full List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, qemu-devel@nongnu.org Cc: stefanha@redhat.com, famz@redhat.com, mreitz@redhat.com, jcody@redhat.com, eblake@redhat.com, pbonzini@redhat.com, Kevin Wolf On 07/14/2016 08:19 PM, Vladimir Sementsov-Ogievskiy wrote: > Mirror can do up to 16 in-flight requests, but actually on full copy > (the whole source disk is non-zero) in-flight is always 1. This happens > as the request is not limited in size: the data occupies maximum available > capacity of s->buf. > > The patch limits the size of the request to some artificial constant > (1 Mb here), which is not that big or small. This effectively enables > back parallelism in mirror code as it was designed. > > The result is important: the time to migrate 10 Gb disk is reduced from > ~350 sec to 170 sec. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > Signed-off-by: Denis V. Lunev > CC: Stefan Hajnoczi > CC: Fam Zheng > CC: Kevin Wolf > CC: Max Reitz > CC: Jeff Cody > CC: Eric Blake > --- > > v2: in case of s->buf_size larger than default use it to limit io_sectors > > block/mirror.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/block/mirror.c b/block/mirror.c > index b1e633e..3ac3b4d 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -23,7 +23,9 @@ > > #define SLICE_TIME 100000000ULL /* ns */ > #define MAX_IN_FLIGHT 16 > -#define DEFAULT_MIRROR_BUF_SIZE (10 << 20) > +#define MAX_IO_SECTORS ((1 << 20) >> BDRV_SECTOR_BITS) /* 1 Mb */ > +#define DEFAULT_MIRROR_BUF_SIZE \ > + (MAX_IN_FLIGHT * MAX_IO_SECTORS * BDRV_SECTOR_SIZE) > > /* The mirroring buffer is a list of granularity-sized chunks. > * Free chunks are organized in a list. > @@ -322,6 +324,8 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) > int nb_chunks = 1; > int64_t end = s->bdev_length / BDRV_SECTOR_SIZE; > int sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; > + int max_io_sectors = MAX((s->buf_size >> BDRV_SECTOR_BITS) / MAX_IN_FLIGHT, > + MAX_IO_SECTORS); > > sector_num = hbitmap_iter_next(&s->hbi); > if (sector_num < 0) { > @@ -385,7 +389,9 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) > nb_chunks * sectors_per_chunk, > &io_sectors, &file); > if (ret < 0) { > - io_sectors = nb_chunks * sectors_per_chunk; > + io_sectors = MIN(nb_chunks * sectors_per_chunk, max_io_sectors); > + } else if (ret & BDRV_BLOCK_DATA) { > + io_sectors = MIN(io_sectors, max_io_sectors); > } > > io_sectors -= io_sectors % sectors_per_chunk; ping