Tunable Kernel Parameters
NAME [Toc] [Back]
scroll_lines - number of scrollable lines used by the Internal
VALUES [Toc] [Back]
Default [Toc] [Back]
Allowed values [Toc] [Back]
60 to 999
Recommended values [Toc] [Back]
No larger than is sufficient for a user's purposes.
DESCRIPTION [Toc] [Back]
This tunable specifies the total number of scroll buffer lines used by
the HP-UX graphics console Internal Terminal Emulator (ITE). This
value is the sum of both on-screen and off-screen lines. For
instance, if the ITE has 68 on-screen lines, and the value of
scroll_lines is 128, then there will be 60 off-screen lines that can
be scrolled back into view.
During boot, the system may adjust the value of scroll_lines upward,
depending upon the installed graphics hardware. On graphics cards
capable of running at more than one resolution, the ITE will first
determine the maximum number of on-screen lines across all possible
resolutions. The ITE will then ensure that scroll_lines is at least
equal to this number of on-screen lines. For example, assume the
graphics card supports two possible resolutions which result in one
ITE resolution of 160 characters by 62 lines and another ITE
resolution of 120 characters by 78 lines. If a value of 62 had been
specified for scroll_lines in the system file, the ITE would then
adjust this value upwards to 78.
Who Is Expected to Change This Tunable?
Restrictions on Changing [Toc] [Back]
Changes to this tunable take effect at the next reboot.
When Should the Value of This Tunable Be Raised?
The value of scroll_line can be increased if the user would like to
retain additional lines in the scroll buffer.
What Are the Side Effects of Raising the Value of This Tunable?
Increasing the size of the ITE scroll buffer consumes kernel memory
which will be dedicated to the ITE and cannot be used for other
purposes by the rest of the system. Memory is used at the rate of 2
Hewlett-Packard Company - 1 - HP-UX 11i Version 2: Sep 2004
Tunable Kernel Parameters
bytes per off-screen character.
When Should the Value of This Tunable Be Lowered?
If the additional off-screen lines in the scroll buffer are not
required, scroll_lines can be decreased to free up a small amount of
memory. The savings will be two bytes per off-screen character. For
instance, if the display is 160 characters wide, decreasing
scroll_lines by 10 will free up 3200 bytes.
What Are the Side Effects of Lowering the Value of This Tunable?
If scroll_lines is set below or equal to the number of lines displayed
on the ITE screen, no off-screen text will be accessible.
What Other Tunables Should Be Changed at the Same Time?
WARNINGS [Toc] [Back]
All HP-UX kernel tunable parameters are release specific. This
parameter may be removed or have its meaning changed in future
releases of HP-UX.
Installation of optional kernel software, from HP or other vendors,
may cause changes to tunable parameter values. After installation,
some tunable parameters may no longer be at the default or recommended
values. For information about the effects of installation on tunable
values, consult the documentation for the kernel software being
installed. For information about optional kernel software that was
factory installed on your system, see HP-UX Release Notes at
AUTHOR [Toc] [Back]
scroll_lines was developed by HP.
Hewlett-Packard Company - 2 - HP-UX 11i Version 2: Sep 2004 [ Back ]