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Move the content lock directly into the BufferDesc, so that locking and pinning a buffer touches only one cache line rather than two. Adjust the definition of BufferDesc slightly so that this doesn't make the BufferDesc any larger than one cache line (at least on platforms where a spinlock is only 1 or 2 bytes). We can't fit the I/O locks into the BufferDesc and stay within one cache line, so move those to a completely separate tranche. This leaves a relatively limited number of LWLocks in the main tranche, so increase the padding of those remaining locks to a full cache line, rather than allowing adjacent locks to share a cache line, hopefully reducing false sharing. Performance testing shows that these changes make little difference on laptop-class machines, but help significantly on larger servers, especially those with more than 2 sockets. Andres Freund, originally based on an earlier patch by Simon Riggs. Review and cosmetic adjustments (including heavy rewriting of the comments) by me.
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: http://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.