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Ceph is a distributed object, block, and file storage platform
c7daaaf5e6
jerasure expects chunk sizes that are aligned on the largest possible vector size that could be used by SSE instructions, when available ( LARGEST_VECTOR_WORDSIZE == 16 bytes ). For techniques derived from Cauchy, encoding and decoding is done by subdividing the chunk into packets of packetsize bytes. The operations are done w * packetsize bytes at a time. It follows that each chunk must have a size that is a multiple of w * packetsize bytes. For techniques derived from Vandermonde, it is enough for a chunk to be a multiple of w * LARGEST_VECTOR_WORDSIZE. ErasureCodeJerasure::get_alignment returns a size alignment constraint that has to be enforced as a multiple of the object size. The resulting object size then has to match the chunk constraints described above although they have no relationship with K. For Cauchy, it leads to excessive padding, making it impossible to set sensible parameters for when the object size is small. When the per_chunk_alignement data member is true, the semantic of ErasureCodeJerasure::get_alignment is changed to return a size alignment constraint to be enforced as a multiple of the chunk size. The ErasureCodeJerasure::get_chunk_size method is modified to use the new semantic when appropriate. The jerasure-per-chunk-alignement parameter is parsed to set per_chunk_alignement for the Vandermonde and Cauchy techniques. The memory address of a chunk is implicitly aligned to a page boundary because it is allocated with buffer::create_page_aligned. http://tracker.ceph.com/issues/8475 Fixes: #8475 Signed-off-by: Loic Dachary <loic@dachary.org> |
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| examples/librados | ||
| fusetrace | ||
| keys | ||
| m4 | ||
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| share | ||
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| autogen.sh | ||
| ceph.spec.in | ||
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| do_autogen.sh | ||
| doc_deps.deb.txt | ||
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| INSTALL | ||
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============================================ Ceph - a scalable distributed storage system ============================================ Please see http://ceph.com/ for current info. Contributing Code ================= Most of Ceph is licensed under the LGPL version 2.1. Some miscellaneous code is under BSD-style license or is public domain. The documentation is licensed under Creative Commons Attribution-ShareAlike (CC BY-SA). There are a handful of headers included here that are licensed under the GPL. Please see the file COPYING for a full inventory of licenses by file. Code contributions must include a valid "Signed-off-by" acknowledging the license for the modified or contributed file. Please see the file SubmittingPatches for details on what that means and on how to generate and submit patches. We do not require assignment of copyright to contribute code; code is contributed under the terms of the applicable license. Building Ceph ============= To build the server daemons, and FUSE client, execute the following: ./autogen.sh ./configure make (Note that the FUSE client will only be built if libfuse is present.) Dependencies ------------ The configure script will complain about any missing dependencies as it goes. You can also refer to debian/control or ceph.spec.in for the package build dependencies on those platforms. In many cases, dependencies can be avoided with --with-foo or --without-bar switches. For example, ./configure --with-nss # use libnss instead of libcrypto++ ./configure --without-radosgw # do not build radosgw ./configure --without-tcmalloc # avoid google-perftools dependency Building packages ----------------- You can build packages for Debian or Debian-derived (e.g., Ubuntu) systems with sudo apt-get install dpkg-dev dpkg-checkbuilddeps # make sure we have all dependencies dpkg-buildpackage For RPM-based systems (Red Hat, SUSE, etc.), rpmbuild Build Prerequisites =================== debian-based ------------ The list of debian package dependencies can be found in deps.deb.txt: sudo apt-get install `cat deps.deb.txt` Note: libsnappy-dev and libleveldb-dev are not available upstream for natty, oneiric, and squeeze. Backports for Ceph can be found at ceph.com/debian-leveldb. rpm-based --------- The list of RPM package dependencies can be found in deps.rpm.txt: sudo yum install `cat deps.rpm.txt` Building the Documentation ========================== Prerequisites ------------- The list of package dependencies for building the documentation can be found in doc_deps.deb.txt: sudo apt-get install `cat doc_deps.deb.txt` Building the Documentation -------------------------- To build the documentation, ensure that you are in the top-level `/ceph directory, and execute the build script. For example: admin/build-doc