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Tue, 27 Aug 2019 16:58:13 +0000 (UTC) Received: from dresden.str.redhat.com (unknown [10.40.205.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5952910016EA; Tue, 27 Aug 2019 16:58:12 +0000 (UTC) To: Nir Soffer , qemu-devel@nongnu.org References: <20190827010528.8818-1-nsoffer@redhat.com> <20190827010528.8818-2-nsoffer@redhat.com> From: Max Reitz Openpgp: preference=signencrypt Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: Date: Tue, 27 Aug 2019 18:58:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190827010528.8818-2-nsoffer@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Au9oWb4IJM8O0cwOP4cCZrsrTDTnXzZqn" X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Tue, 27 Aug 2019 16:58:14 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v3 1/2] block: posix: Always allocate the first block X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Nir Soffer , qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --Au9oWb4IJM8O0cwOP4cCZrsrTDTnXzZqn Content-Type: multipart/mixed; boundary="8RqCYTtfslKgw2m49URRyUpVqC6Pt8rud"; protected-headers="v1" From: Max Reitz To: Nir Soffer , qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Nir Soffer Message-ID: Subject: Re: [PATCH v3 1/2] block: posix: Always allocate the first block References: <20190827010528.8818-1-nsoffer@redhat.com> <20190827010528.8818-2-nsoffer@redhat.com> In-Reply-To: <20190827010528.8818-2-nsoffer@redhat.com> --8RqCYTtfslKgw2m49URRyUpVqC6Pt8rud Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 27.08.19 03:05, Nir Soffer wrote: > When creating an image with preallocation "off" or "falloc", the first > block of the image is typically not allocated. When using Gluster > storage backed by XFS filesystem, reading this block using direct I/O > succeeds regardless of request length, fooling alignment detection. >=20 > In this case we fallback to a safe value (4096) instead of the optimal > value (512), which may lead to unneeded data copying when aligning > requests. Allocating the first block avoids the fallback. >=20 > Since we allocate the first block even with preallocation=3Doff, we no > longer create images with zero disk size: >=20 > $ ./qemu-img create -f raw test.raw 1g > Formatting 'test.raw', fmt=3Draw size=3D1073741824 >=20 > $ ls -lhs test.raw > 4.0K -rw-r--r--. 1 nsoffer nsoffer 1.0G Aug 16 23:48 test.raw >=20 > And converting the image requires additional cluster: >=20 > $ ./qemu-img measure -f raw -O qcow2 test.raw > required size: 458752 > fully allocated size: 1074135040 >=20 > When using format like vmdk with multiple files per image, we allocate > one block per file: >=20 > $ ./qemu-img create -f vmdk -o subformat=3DtwoGbMaxExtentFlat test.= vmdk 4g > Formatting 'test.vmdk', fmt=3Dvmdk size=3D4294967296 compat6=3Doff = hwversion=3Dundefined subformat=3DtwoGbMaxExtentFlat >=20 > $ ls -lhs test*.vmdk > 4.0K -rw-r--r--. 1 nsoffer nsoffer 2.0G Aug 27 03:23 test-f001.vmdk= > 4.0K -rw-r--r--. 1 nsoffer nsoffer 2.0G Aug 27 03:23 test-f002.vmdk= > 4.0K -rw-r--r--. 1 nsoffer nsoffer 353 Aug 27 03:23 test.vmdk >=20 > I did quick performance test for copying disks with qemu-img convert to= > new raw target image to Gluster storage with sector size of 512 bytes: >=20 > for i in $(seq 10); do > rm -f dst.raw > sleep 10 > time ./qemu-img convert -f raw -O raw -t none -T none src.raw d= st.raw > done >=20 > Here is a table comparing the total time spent: >=20 > Type Before(s) After(s) Diff(%) > --------------------------------------- > real 530.028 469.123 -11.4 > user 17.204 10.768 -37.4 > sys 17.881 7.011 -60.7 >=20 > We can see very clear improvement in CPU usage. >=20 > Signed-off-by: Nir Soffer > --- > block/file-posix.c | 51 +++++++++++++++++++= > tests/qemu-iotests/059.out | 2 +- > tests/qemu-iotests/{150.out =3D> 150.out.qcow2} | 0 > tests/qemu-iotests/150.out.raw | 12 +++++ > tests/qemu-iotests/175 | 19 ++++--- > tests/qemu-iotests/175.out | 8 +-- > tests/qemu-iotests/178.out.qcow2 | 4 +- > tests/qemu-iotests/221.out | 12 +++-- > tests/qemu-iotests/253.out | 12 +++-- > 9 files changed, 99 insertions(+), 21 deletions(-) > rename tests/qemu-iotests/{150.out =3D> 150.out.qcow2} (100%) > create mode 100644 tests/qemu-iotests/150.out.raw Reviewed-by: Max Reitz Maybe it=E2=80=99ll break the vmdk iotests when using a non-default subfo= rmat; but currently running the iotests for non-default VMDK subformats is broken anyway, so it doesn=E2=80=99t matter. Max --8RqCYTtfslKgw2m49URRyUpVqC6Pt8rud-- --Au9oWb4IJM8O0cwOP4cCZrsrTDTnXzZqn Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl1lYSIACgkQ9AfbAGHV z0CYwQf/TBizHz+kGDIGC7+ARSCDc/9u7rqveyQlqZQXiiIkt4KE7RPSWxGuNKp1 ownnLKCQ7VAIKA3yFvYcS3/+9REIay9mFvMPmjELQSQgoCYkrwAT6c+4oP2fh0w/ PSZoHZY5xj8iRCL5wXl3tFecgTZe1QWWH7Rn42QAzhK1Ryq4EVby9VOw+tpSiMjA Fl7BuwwL5UoL524yjaEU8f7bEDxRO8/uiImSs5G1YUrdVe3auei6r8kgVwt/IDpj whF5tBuaL9V3XayNSho8aFVaweZU84E2OoA/4f///+jMi1lOis7ieRV4PmYf1cLl 0BiaDUeoJsuXj2qf7JHEmRcI7Jlirw== =VdMf -----END PGP SIGNATURE----- --Au9oWb4IJM8O0cwOP4cCZrsrTDTnXzZqn--