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When the system is idle for awhile after activity, the "smoothed_alloc" state variable in BgBufferSync converges slowly to zero. With standard IEEE float arithmetic this results in several iterations with denormalized values, which causes kernel traps and annoying log messages on some poorly-designed platforms. There's no real need to track such small values of smoothed_alloc, so we can prevent the kernel traps by forcing it to zero as soon as it's too small to be interesting for our purposes. This issue is purely cosmetic, since the iterations don't happen fast enough for the kernel traps to pose any meaningful performance problem, but still it seems worth shutting up the log messages. The kernel log messages were previously reported by a number of people, but kudos to Greg Matthews for tracking down exactly where they were coming from.
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. Changes between all PostgreSQL releases are recorded in the file HISTORY. 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/.