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Tue, 27 Aug 2019 17:10:51 +0000 (UTC) Received: from dresden.str.redhat.com (unknown [10.40.205.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2C82E5DC18; Tue, 27 Aug 2019 17:10:49 +0000 (UTC) From: Max Reitz To: Nir Soffer , qemu-devel@nongnu.org References: <20190827010528.8818-1-nsoffer@redhat.com> <20190827010528.8818-2-nsoffer@redhat.com> 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: <999ec4b9-7f7c-ab4f-0ee5-04a4eb9be4ad@redhat.com> Date: Tue, 27 Aug 2019 19:10:48 +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: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="zKmA00dHHZfGaoHNleq4J3J1TAeFcLHPX" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.62]); Tue, 27 Aug 2019 17:10:51 +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) --zKmA00dHHZfGaoHNleq4J3J1TAeFcLHPX Content-Type: multipart/mixed; boundary="aUGfzH0g0iaqnn2tVEu9hcDlCApS4ARIo"; protected-headers="v1" From: Max Reitz To: Nir Soffer , qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Nir Soffer Message-ID: <999ec4b9-7f7c-ab4f-0ee5-04a4eb9be4ad@redhat.com> 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: --aUGfzH0g0iaqnn2tVEu9hcDlCApS4ARIo Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 27.08.19 18:58, Max Reitz wrote: > 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. >> >> 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. >> >> Since we allocate the first block even with preallocation=3Doff, we no= >> longer create images with zero disk size: >> >> $ ./qemu-img create -f raw test.raw 1g >> Formatting 'test.raw', fmt=3Draw size=3D1073741824 >> >> $ ls -lhs test.raw >> 4.0K -rw-r--r--. 1 nsoffer nsoffer 1.0G Aug 16 23:48 test.raw >> >> And converting the image requires additional cluster: >> >> $ ./qemu-img measure -f raw -O qcow2 test.raw >> required size: 458752 >> fully allocated size: 1074135040 >> >> When using format like vmdk with multiple files per image, we allocate= >> one block per file: >> >> $ ./qemu-img create -f vmdk -o subformat=3DtwoGbMaxExtentFlat test= =2Evmdk 4g >> Formatting 'test.vmdk', fmt=3Dvmdk size=3D4294967296 compat6=3Doff= hwversion=3Dundefined subformat=3DtwoGbMaxExtentFlat >> >> $ ls -lhs test*.vmdk >> 4.0K -rw-r--r--. 1 nsoffer nsoffer 2.0G Aug 27 03:23 test-f001.vmd= k >> 4.0K -rw-r--r--. 1 nsoffer nsoffer 2.0G Aug 27 03:23 test-f002.vmd= k >> 4.0K -rw-r--r--. 1 nsoffer nsoffer 353 Aug 27 03:23 test.vmdk >> >> I did quick performance test for copying disks with qemu-img convert t= o >> new raw target image to Gluster storage with sector size of 512 bytes:= >> >> 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 = dst.raw >> done >> >> Here is a table comparing the total time spent: >> >> 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 >> >> We can see very clear improvement in CPU usage. >> >> 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 >=20 > Reviewed-by: Max Reitz >=20 > Maybe it=E2=80=99ll break the vmdk iotests when using a non-default sub= format; > but currently running the iotests for non-default VMDK subformats is > broken anyway, so it doesn=E2=80=99t matter. (Good news, 059 really was the only issue for VMDK.) --aUGfzH0g0iaqnn2tVEu9hcDlCApS4ARIo-- --zKmA00dHHZfGaoHNleq4J3J1TAeFcLHPX Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl1lZBgACgkQ9AfbAGHV z0DxlAf/dn0+W4vjAwGluOv+/Bv/n5w7VssCjqG5Ni3aCFwG1y8dWnEl5eP42Vqx eP3ozFUr7IztTAnAw4zWUAYF4RrnohWFrF7PLoZx1OzT/OUyI8rdoNIPSbCcz5Zg k3pSIr2OxHWrGk6TQVZ6peCm76+EAZvZ9mBE6M8OGCuOm49JV8xGCy98vevrA9PA ND8RfvMrSSGWWZFg3VmH6c+RpTWMQGN0qSxBre1/Gs2/afIxQ0RxSbr3aY+sNm23 XGnokgKa/L0sp9KJG2VsyvtxlcEeZ6lJ/cgGrLBBBMWOdDlTZy4g0LsyNFKsD+WF pQN9xR4Q3m3KQj5xk01LNQOOq2Bzuw== =YJm/ -----END PGP SIGNATURE----- --zKmA00dHHZfGaoHNleq4J3J1TAeFcLHPX--