<para>

<application>pg_test_fsync</> is intended to give you a reasonable

idea of what the fastest fsync_method is on your specific system,

idea of what the fastest <xref linkend="guc-wal-sync-method"> is on your

specific system,

as well as supplying diagnostic information in the event of an

identified I/O problem. However, differences shown bytest_fsync

identified I/O problem. However, differences shown bypg_test_fsync

might not make any difference in real database throughput, especially

since many database servers are not speed-limited by their transaction

logs.

<sect2>

<title>Usage</title>

<sect2>

<title><application>pg_test_fsync</> Options</title>

<synopsis>

pg_test_fsync [options]

</synopsis>

<para>

<application>pg_test_fsync</application> accepts the following command-line arguments:

<application>pg_test_fsync</application> accepts the following

command-line options:

<variablelist>

<term><option>--filename</option></term>

<listitem>

<para>

Specifies the filename for test. The file should be in the

same file system as the <filename>pg_xlog</> directory.

<filename>/pg_xlog</> contains the <acronym>WAL</> files.)

Specifies the filename to write test data in.

This file should be in the same file system that the

<filename>pg_xlog</> directory is or will be placed in.

(<filename>pg_xlog</> contains the <acronym>WAL</> files.)

The default is <filename>test_fsync.out</> in the current

directory.

</para>

<listitem>

<para>

Specifies the number of operations per test. The more operations

per test, the greater the test's accuracy. The default is

2000.

per test, the greater the test's accuracy, but the longer it takes

to run. The default is2000.

</para>

</listitem>

</varlistentry>