NAME
scroll_lines — number of scrollable lines used by the Internal Terminal Emulator
VALUES
Recommended values
No larger than is sufficient for a user's purposes.
DESCRIPTION
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?
Anyone.
Restrictions on Changing
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 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?
None.
WARNINGS
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
http://docs.hp.com.
AUTHOR
scroll_lines
was developed by HP.
Printable version
