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Tom Lane 5461564a9d Reduce idle power consumption of walwriter and checkpointer processes.
This patch modifies the walwriter process so that, when it has not found
anything useful to do for many consecutive wakeup cycles, it extends its
sleep time to reduce the server's idle power consumption.  It reverts to
normal as soon as it's done any successful flushes.  It's still true that
during any async commit, backends check for completed, unflushed pages of
WAL and signal the walwriter if there are any; so that in practice the
walwriter can get awakened and returned to normal operation sooner than the
sleep time might suggest.

Also, improve the checkpointer so that it uses a latch and a computed delay
time to not wake up at all except when it has something to do, replacing a
previous hardcoded 0.5 sec wakeup cycle.  This also is primarily useful for
reducing the server's power consumption when idle.

In passing, get rid of the dedicated latch for signaling the walwriter in
favor of using its procLatch, since that comports better with possible
generic signal handlers using that latch.  Also, fix a pre-existing bug
with failure to save/restore errno in walwriter's signal handlers.

Peter Geoghegan, somewhat simplified by Tom
2012-05-08 20:03:26 -04:00
config Update config.guess and config.sub 2012-05-08 20:46:13 +03:00
contrib Tweak contrib --help output to match common style 2012-05-08 21:55:05 +03:00
doc psql: Add variable to control keyword case in tab completion 2012-05-08 21:06:08 +03:00
src Reduce idle power consumption of walwriter and checkpointer processes. 2012-05-08 20:03:26 -04:00
.gitignore Add gitignore for mingw/cygwin build outputs 2011-06-09 18:11:47 +02:00
COPYRIGHT Update copyright notices for year 2012. 2012-01-01 18:01:58 -05:00
GNUmakefile.in Add isolation test to check-world and installcheck-world 2012-03-05 20:19:20 +02:00
Makefile Allow make check in PL directories 2011-02-15 06:52:12 +02:00
README Remove useless whitespace at end of lines 2010-11-23 22:34:55 +02:00
README.git Trivial typo fix. 2010-09-21 14:16:00 -04:00
aclocal.m4 Remove cvs keywords from all files. 2010-09-20 22:08:53 +02:00
configure Remove strdup, strtol, strtoul from libpgport 2012-05-07 23:10:28 +03:00
configure.in Remove strdup, strtol, strtoul from libpgport 2012-05-07 23:10:28 +03:00

README

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/.