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Thu, 30 Apr 2020 08:26:06 +0000 (UTC) Subject: Re: [PATCH v22 3/4] qcow2: add zstd cluster compression To: Vladimir Sementsov-Ogievskiy , Denis Plotnikov , qemu-devel@nongnu.org References: <20200428200013.24474-1-dplotnikov@virtuozzo.com> <20200428200013.24474-4-dplotnikov@virtuozzo.com> <23f0a79a-6e8d-3702-3d82-9db54a442a5f@virtuozzo.com> From: Max Reitz 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: <73ebc101-7148-2b38-492f-538d4bf8c8a4@redhat.com> Date: Thu, 30 Apr 2020 10:26:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <23f0a79a-6e8d-3702-3d82-9db54a442a5f@virtuozzo.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="3mBCjFW98SzB9s1vI1oQyTwIaL9mtpy0L" Received-SPF: pass client-ip=207.211.31.120; envelope-from=mreitz@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/29 23:34:52 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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: kwolf@redhat.com, berto@igalia.com, qemu-block@nongnu.org, armbru@redhat.com, den@openvz.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) --3mBCjFW98SzB9s1vI1oQyTwIaL9mtpy0L Content-Type: multipart/mixed; boundary="UYQb2UJGxeTWCYce0x1MiEOhfzXvWOO1h" --UYQb2UJGxeTWCYce0x1MiEOhfzXvWOO1h Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 29.04.20 15:02, Vladimir Sementsov-Ogievskiy wrote: > 29.04.2020 15:17, Max Reitz wrote: >> On 29.04.20 12:37, Vladimir Sementsov-Ogievskiy wrote: >>> 29.04.2020 13:24, Max Reitz wrote: >>>> On 28.04.20 22:00, Denis Plotnikov wrote: >>>>> zstd significantly reduces cluster compression time. >>>>> It provides better compression performance maintaining >>>>> the same level of the compression ratio in comparison with >>>>> zlib, which, at the moment, is the only compression >>>>> method available. >>>>> >>>>> The performance test results: >>>>> Test compresses and decompresses qemu qcow2 image with just >>>>> installed rhel-7.6 guest. >>>>> Image cluster size: 64K. Image on disk size: 2.2G >>>>> >>>>> The test was conducted with brd disk to reduce the influence >>>>> of disk subsystem to the test results. >>>>> The results is given in seconds. >>>>> >>>>> compress cmd: >>>>> =A0=A0=A0 time ./qemu-img convert -O qcow2 -c -o >>>>> compression_type=3D[zlib|zstd] >>>>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 src.img [zl= ib|zstd]_compressed.img >>>>> decompress cmd >>>>> =A0=A0=A0 time ./qemu-img convert -O qcow2 >>>>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 [zlib|zstd]= _compressed.img uncompressed.img >>>>> >>>>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 compression=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0 decompression >>>>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 zlib=A0=A0=A0=A0=A0=A0 zstd=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0 zlib=A0=A0=A0=A0=A0=A0=A0=A0 zstd >>>>> ------------------------------------------------------------ >>>>> real=A0=A0=A0=A0 65.5=A0=A0=A0=A0=A0=A0 16.3 (-75 %)=A0=A0=A0 1.9=A0= =A0=A0=A0=A0=A0=A0=A0=A0 1.6 (-16 %) >>>>> user=A0=A0=A0=A0 65.0=A0=A0=A0=A0=A0=A0 15.8=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0 5.3=A0=A0=A0=A0=A0=A0=A0=A0=A0 2.5 >>>>> sys=A0=A0=A0=A0=A0=A0 3.3=A0=A0=A0=A0=A0=A0=A0 0.2=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0 2.0=A0=A0=A0=A0=A0=A0=A0=A0=A0 2.0 >>>>> >>>>> Both ZLIB and ZSTD gave the same compression ratio: 1.57 >>>>> compressed image size in both cases: 1.4G >>>>> >>>>> Signed-off-by: Denis Plotnikov >>>>> QAPI part: >>>>> Acked-by: Markus Armbruster >>>>> --- >>>>> =A0=A0 docs/interop/qcow2.txt |=A0=A0 1 + >>>>> =A0=A0 configure=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 |=A0=A0 2 +- >>>>> =A0=A0 qapi/block-core.json=A0=A0 |=A0=A0 3 +- >>>>> =A0=A0 block/qcow2-threads.c=A0 | 169 >>>>> +++++++++++++++++++++++++++++++++++++++++ >>>>> =A0=A0 block/qcow2.c=A0=A0=A0=A0=A0=A0=A0=A0=A0 |=A0=A0 7 ++ >>>>> =A0=A0 slirp=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 |=A0= =A0 2 +- >>>>> =A0=A0 6 files changed, 181 insertions(+), 3 deletions(-) >>>> >>>> [...] >>>> >>>>> diff --git a/block/qcow2-threads.c b/block/qcow2-threads.c >>>>> index 7dbaf53489..a0b12e1b15 100644 >>>>> --- a/block/qcow2-threads.c >>>>> +++ b/block/qcow2-threads.c >>>> >>>> [...] >>>> >>>>> +static ssize_t qcow2_zstd_decompress(void *dest, size_t dest_size, >>>>> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 const void *src, size_t >>>>> src_size) >>>>> +{ >>>> >>>> [...] >>>> >>>>> +=A0=A0=A0 /* >>>>> +=A0=A0=A0=A0 * The compressed stream from the input buffer may consi= st of >>>>> more >>>>> +=A0=A0=A0=A0 * than one zstd frame. >>>> >>>> Can it? >>> >>> If not, we must require it in the specification. >> >> Actually, now that you mention it, it would make sense anyway to add >> some note to the specification on what exactly compressed with zstd >> means. >> >>> Hmm. If at some point >>> we'll want multi-threaded compression of one big (2M) cluster.. Could >>> this be implemented with zstd lib, if multiple frames are allowed, will >>> allowing multiple frames help? I don't know actually, but I think bette= r >>> not to forbid it. On the other hand, I don't see any benefit in large >>> compressed clusters. At least, in our scenarios (for compressed backups= ) >>> we use 64k compressed clusters, for good granularity of incremental >>> backups (when for running vm we use 1M clusters). >> >> Is it really that important?=A0 Na=EFvely, it sounds rather complicated = to >> introduce multithreading into block drivers. >=20 > It is already here: compression and encryption already multithreaded. > But of course, one cluster is handled in one thread. Ah, good. I forgot. >> (Also, as for compression, it can only be used in backup scenarios >> anyway, where you write many clusters at once.=A0 So parallelism on the >> cluster level should sufficient to get high usage, and it would benefit >> all compression types and cluster sizes.) >> >=20 > Yes it works in this way already :) Well, OK then. > So, we don't know do we want one frame restriction or not. Do you have a > preference? *shrug* Seems like it would be preferential to allow multiple frames still. A note in the spec would be nice (i.e., streaming format, multiple frames per cluster possible). Max --UYQb2UJGxeTWCYce0x1MiEOhfzXvWOO1h-- --3mBCjFW98SzB9s1vI1oQyTwIaL9mtpy0L Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl6qi50ACgkQ9AfbAGHV z0DKVwf/QHywNtCkds5M7i7YOwtlhCjglcmdhSoacC70NCD7P3+zj18VzkI7zet6 ruPqBC8+eTFybHztxJe9m4gorquqR24ixYxXPLhm48ISyVX8rc9jZpwxQ6nCXIsi 3Iu47FJfgbvhBjb9UuzHsGtwRU98WNjXs8PIOFs73teEMjEbGAvV9txtTxMEXQHX /T0bJt+cIwi5kWilmXklxpwpgYUiEaur3Q4RkDJwXI+yZbAdLDOiY84F6cuaIIbw DeK1WpkElYsWib1osRz8uuau06ecC7W2Pakv2Pl/oFl/ymQrSUXDlENEGbDhL5sK uq2yBHlKO1aypNM6/YlNhpcbbhq1eA== =x5lX -----END PGP SIGNATURE----- --3mBCjFW98SzB9s1vI1oQyTwIaL9mtpy0L--