tuneinfo2(2) tuneinfo2(2)
NAME [Toc] [Back]
tuneinfo2 - retrieve detailed information about kernel tunable
parameters
SYNOPSIS [Toc] [Back]
#include <sys/dyntune.h>
int tuneinfo2(int version,
const char *tunable,
tuneinfo2_t *buf,
size_t *bufsize);
TUNEINFO_STRING(tunable, string)
DESCRIPTION [Toc] [Back]
This function provides detailed information about one or all kernel
tunable parameters. If a particular parameter is of interest, specify
it by name in tunable. Otherwise, set tunable to NULL and information
will be returned on all kernel tunable parameters (if the supplied
buffer is big enough).
version must always be set to TUNEINFO_VERSION.
Information about the selected tunable parameters is returned in
tuneinfo2_t structures and associated character strings. The buf
parameter must specify an address in the caller's space containing
space for these structures and strings.
bufsize must point to a variable containing the size of the buffer (in
bytes).
Since the character strings are of variable length, the caller must
first ask how much buffer space is needed, then allocate the necessary
buffer space, and then ask for the tunable information. To calculate
the size of the buffer to hold all the tunables, this function should
be called with the parameters buf and bufsize set to NULL and zero,
respectively. The function will return successfully with a return
value of 0 and the variable at bufsize will have been changed to
contain the amount of space needed to hold all of the requested data.
See the example below.
Each tuneinfo2_t structure describes a single tunable parameter, and
contains at least the following fields, in unspecified order:
uint64_t ti_name;
Location of the character string containing the name of the
tunable.
uint64_t ti_oldname;
Location of the character string containing the old name of
the tunable. Some tunables have older, shorter names that
Hewlett-Packard Company - 1 - HP-UX 11i Version 2: August 2003
tuneinfo2(2) tuneinfo2(2)
are still recognized for compatibility purposes. Those
tunables have their older names given here. Tunables
without an older name have a null string here.
uint64_t ti_desc;
Location of the character string containing an English
description of the parameter.
uint64_t ti_module;
Location of the character string containing name of the DLKM
module in which the parameter is defined. This will be a
null string for those parameters defined in the core kernel.
uint64_t ti_current;
The current value of the parameter.
uint64_t ti_bootvalue;
The boot-time value of the parameter.
uint64_t ti_default;
The HP-supplied default value of the parameter.
uint64_t ti_min;
The minimum value of the parameter. Valid only if the
TIF_MINVALID flag is set in the ti_flags word, below.
uint64_t ti_max;
The maximum value of the parameter. Valid only if the
TIF_MAXVALID flag is set in the ti_flags word, below.
Note: The minimum and maximum values returned here are
relatively static limits. They will reflect the limitations
of the operating system software, and any limitations placed
on this tunable parameter by the current values of other
tunable parameters. However, they do not reflect any
restrictions on the tunable value based on transient factors
like the current usage pattern of the system.
For example, the maximum value returned for maxfiles (the
number of files a process may have open) will be no greater
than the current value of nfile (the number of files the
system may have open). However, the minimum value returned
for maxfiles may very well be less than the number of files
that some existing process has open.
uint64_t ti_flags;
A bitmask of zero or more of the following flags:
TIF_CANSET The value of this parameter can be changed
using settune().
Hewlett-Packard Company - 2 - HP-UX 11i Version 2: August 2003
tuneinfo2(2) tuneinfo2(2)
TIF_DYNAMIC The value of this parameter can be changed
using settune(), without requiring a
reboot.
TIF_SIGNED The values, minima and maxima, for this
parameter should be interpreted as signed
quantities.
TIF_MINVALID The ti_minimum field contains a minimum
allowed value for this parameter.
TIF_MAXVALID The ti_maximum field contains a maximum
allowed value for this parameter.
The character string location fields, ti_name, ti_oldname, ti_desc,
and ti_module, can be used to retrieve the character strings. These
fields must be accessed using the TUNEINFO_STRING() macro. The first
parameter of the macro is the pointer to the tuneinfo2_t structure and
the second parameter is one of the four field names above. The result
of the macro will be a pointer to a null-terminated string. See the
example below.
RETURN VALUE [Toc] [Back]
If tuneinfo2() is successful, it returns the number of tunable
parameters for which information was returned and sets the value of
bufsize to the amount of buffer space used. When the parameters buf
and bufsize are set to NULL and zero, respectively; it returns 0 and
sets the value of bufsize to the amount of buffer space that needs to
be preallocated.
ERRORS [Toc] [Back]
If this function returns -1 to indicate an error, the global variable
errno will be set to one of the following values, to indicate the
error that occurred:
[ENOENT] The specified tunable parameter does not exist.
[ENOSPC] The space in buf, as specified in bufsize, is not
sufficient to hold the requested data.
[EFAULT] tunable, buf, or bufsize contains an address that
is inaccessible.
[EIO] The Kernel Registry Service was unavailable or
encountered an error.
[EINVAL] The version is not supported.
EXAMPLES [Toc] [Back]
#include <stdlib.h>
#include <stdio.h>
Hewlett-Packard Company - 3 - HP-UX 11i Version 2: August 2003
tuneinfo2(2) tuneinfo2(2)
#include <sys/dyntune.h>
...
tuneinfo2_t *buf;
size_t bufsize;
int ret;
int count;
int i;
/* To gather information on all tunables: */
/* 1. Find out how much space we need: */
bufsize = 0;
ret = tuneinfo2(TUNEINFO_VERSION, NULL, NULL, &bufsize);
if (ret) {
...
}
/* 2. Allocate that much space: */
buf = (tuneinfo2_t *)malloc(bufsize);
if (buf == NULL) {
...
}
/* 3. Query the data: */
count = tuneinfo2(TUNEINFO_VERSION, NULL, buf, &bufsize);
if (count < 0) {
...
}
/* 4. Print the names of all tunables: */
for (i = 0; i < count; i++) {
char *name = TUNEINFO_STRING(&buf[i], ti_name);
puts(name);
}
WARNINGS [Toc] [Back]
Applications and application modules must not share tuneinfo2_t
structures unless it is certain that the value of TUNEINFO_VERSION,
specified in the <sys/dyntune.h> header file, is the same for all
modules and involved. The value of TUNEINFO_VERSION may be changed
without notice.
AUTHOR [Toc] [Back]
tuneinfo2() was developed by Hewlett-Packard Company.
SEE ALSO [Toc] [Back]
kctune(1M), gettune(2), settune(2), and the individual tunable
parameter man pages in section 5.
Hewlett-Packard Company - 4 - HP-UX 11i Version 2: August 2003 [ Back ] |
