From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59886) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bD0hU-0006vT-9Q for qemu-devel@nongnu.org; Tue, 14 Jun 2016 22:37:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bD0hS-0004pI-66 for qemu-devel@nongnu.org; Tue, 14 Jun 2016 22:37:03 -0400 References: <1465917916-22348-1-git-send-email-den@openvz.org> <1465917916-22348-4-git-send-email-den@openvz.org> From: Eric Blake Message-ID: <5760BF45.9020707@redhat.com> Date: Tue, 14 Jun 2016 20:36:53 -0600 MIME-Version: 1.0 In-Reply-To: <1465917916-22348-4-git-send-email-den@openvz.org> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="S2MDeD5Na8o4TCwriR3mE8UQHcTokxb7w" Subject: Re: [Qemu-devel] [PATCH 3/9] mirror: optimize dirty bitmap filling in mirror_run a bit List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Denis V. Lunev" , qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: vsementsov@virtuozzo.com, Stefan Hajnoczi , Fam Zheng , Kevin Wolf , Max Reitz , Jeff Cody This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --S2MDeD5Na8o4TCwriR3mE8UQHcTokxb7w Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 06/14/2016 09:25 AM, Denis V. Lunev wrote: > There is no need to scan allocation tables if we have mark_all_dirty fl= ag > set. Just mark it all dirty. >=20 > Signed-off-by: Denis V. Lunev > Reviewed-by: Vladimir Sementsov-Ogievskiy > CC: Stefan Hajnoczi > CC: Fam Zheng > CC: Kevin Wolf > CC: Max Reitz > CC: Jeff Cody > CC: Eric Blake > --- > block/mirror.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) >=20 > diff --git a/block/mirror.c b/block/mirror.c > index 797659d..c7b3639 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -507,12 +507,16 @@ static int mirror_dirty_init(MirrorBlockJob *s) > BlockDriverState *base =3D s->base; > BlockDriverState *bs =3D blk_bs(s->common.blk); > BlockDriverState *target_bs =3D blk_bs(s->target); > - bool mark_all_dirty =3D base =3D=3D NULL && !bdrv_has_zero_init(ta= rget_bs); > uint64_t last_pause_ns; > int ret, n; > =20 > end =3D s->bdev_length / BDRV_SECTOR_SIZE; > =20 > + if (base =3D=3D NULL && !bdrv_has_zero_init(target_bs)) { > + bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end); Won't work as written. 'end' is 64 bits, but bdrv_set_dirty_bitmap() is limited to a 32-bit sector count. Might be first worth updating bdrv_set_dirty_bitmap() and friends to be byte-based rather than sector-based (but still tracking a sector per bit, obviously), as well as expand it to operate on 64-bit sizes rather than 32-bit. I'm also worried slightly that the existing code repeated things in a loop, and therefore had pause points every iteration and could thus remain responsive to an early cancel. But doing the entire operation in one chunk (assuming you fix bitmap code to handle a 64-bit size) may end up running for so long without interruption that you lose the benefits of an early interruption that you have by virtue of a 32-bit limit. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --S2MDeD5Na8o4TCwriR3mE8UQHcTokxb7w Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJXYL9FAAoJEKeha0olJ0NqZccIAJkZ1zU5uqKtv94n6e8mMkvO IrKqTN4MbskRY8QzdZ7o9BKn3X+G4clHzRBUMkM9reDPbKEi8JxSo8CLmo8Cy35B fI6O+RhS4VUxUbIhIHkFmkD+ImWWfCwhaExQRkWsZxLYD3Shxvi6/2KHGEleniGJ HKkTJ7JHYnQedq+C3JsqVQ/Ba3cwOGOogfZXy//88nXTCS9qN2Z/VidQcZfVBNgF rGgl+P+xv4W7R2Y5oDmuYYXhmLRlHBUzADwy/yF0xrvbFEoDq9l3CMCNvSVaDLSn VLeRMTOguVKk/Uw3e8yAYnicRLwETwspmllZ6UptN8cfwBZjxaM5LdbYcZ6dQ+4= =y3Sz -----END PGP SIGNATURE----- --S2MDeD5Na8o4TCwriR3mE8UQHcTokxb7w--